These irresistible cookie bars are known around here as Molly Beth Bars. They’re thick, soft bars filled with the trifecta: peanut butter, chocolate, and oats. This easy dessert recipe is an instant hit with both kids and adults alike!
These cookie bars have withstood the test of time. They’re a classic family favorite, and they were the FIRST EVER recipe post on Fork in the Kitchen. HELLO, NOSTALGIA.
The photos have since been updated (thank goodness for growth, am I right?!) but the recipe is the same as the day my mom first made them, and they’re still every bit as delicious.
Since their first appearance, the world has enjoyed Molly Beth Bars for potlucks, weeknight sweet tooth cravings, holiday desserts, sleepover parties, and more. If you’ve made your way here from those original images on Pinterest, just know these are the same bars we’ve all fallen in love with.
Regardless of what your childhood was like, I’m willing to take a gamble that the combination of gooey peanut butter, melty chocolate, and chewy oats is going to take you immediately to your kid-favorite happy place.
These cookie bars just do that to you.
They’re the combination of ultimate comfort, sweet-tooth-fix, and childhood favorites.
They’re addictingly delicious.
They’re a dream come true.
Yes, yes they are. You know, I know it, and there’s absolutely no denying it.
While this classic combination of peanut butter and chocolate needs just about zero words, there is a little history I must share. A history to be told for posterity’s sake, as this was the first Fork in the Kitchen recipe and it holds so many dear memories. So there’s no way I’m leaving out the origin story for Molly Beth Bars (their actual name). Without further ado…
The Story Behind Molly Beth Cookie Bars
As mentioned, these cookie bars are a classic family favorite.
I’m talking as much a part of my childhood as the classic peanut butter and jelly. As much as ice cream cones on hot summer nights, as much as – no, actually more than – chocolate chip cookies.
Even before my time, they were a family tradition. My mom’s older sister, Mandy, had a recipe from somewhere along the lines during her time in girl scouts. As it evolved over the years, no one could remember the actual name of the recipe, and we referred to them as Mandy Bars in the beginning.
That is, until I was in high school when I was eating these bars on a regular basis.
My mom continued to update the recipe for the bars over the years. As in, she added heaping amounts of peanut butter and chocolate chips each time my brother and I begged politely asked her to make them. Because how could you not add just a little more goodness to something already amazing?
Thus, grew the name Molly Beth Bars, after my mom and her spin on the recipe, and her now-famous cookie bar legacy.
Back then, there was a period of time when these bars were made weekly, only to maybe last to the next day.
Luckily, I would often dig into a warm pan of gooey, melty bars after hours of dance practice, which made me feel like I could justify downing half of a pan in one sitting. No joke.
Unfortunately, those dance days are long gone, but I have this magic power of justifying sitting down with a pan of warm Molly Beth Bars and a fork, all to myself. It’s what I like to call “self-care”.
Late-night chocolate chip peanut butter cookie bar cravings, here I come!
How to Make the Ultimate Cookie Bars
Disclaimer: once you make these for dessert, you will not be able to stop.
You will especially not be able to resist because they are so dang easy to make. One mixing bowl, an electric mixer, and a spatula later, you’ll have these indulgent bars baking away in the oven. Don’t even want to use an electric mixer? Go ahead and use a whisk and some muscles. I got you.
The simple ingredient list goes like this:
- butter
- flour
- granulated and brown sugar
- baking soda
- vanilla
- egg
- creamy peanut butter
- oats
- chocolate chips
You will notice the word heaping gets used a lot. That’s because the beauty of this recipe is that you definitely want to overflow the peanut butter and chocolate chip measuring cups.
That is not a science. No, that’s an art, and my friends, the more the better. Which is exactly why I haven’t updated the recipe to say what ‘heaping’ might be, because friends, you’ve got to follow your gut on that part.
The hardest part is waiting for the peanut butter oatmeal chocolate chip bars to cool ever so slightly so they don’t crumble apart.
This may or may not work for me. I give you full permission to dig in and eat the crumbles with a fork, bar be gone until later (when you’re ready for round two).
Yes, you’ve been warned, eat these babies just warm out of the oven and you have my full permission to indulge freely. No judgment here for consuming more than what others may deem as “socially acceptable”. In fact, what is “socially acceptable” when it comes to these babies? It is, in fact, digging straight in.
Seriously, make them and you’ll understand. When it comes to these bars, you cannot go wrong. Unless of course, you’re not eating them. Then that’s nearly a sin.
Frequently Asked Questions
By golly you’ve got the right idea. Yes, you can double this recipe and make the bars in a 9×13 pan, just watch the bake time as they may be done a little sooner.
I haven’t tested it myself and wouldn’t necessarily recommend using almond or coconut flour. You may be able to use 1:1 gluten-free flour if needed. If you do, I’d love to hear how they turn out!
Yep, you can play around with add-ins. Many people have reported that they’ve added nuts to the batter and enjoyed it. M&Ms or peanut butter chips are other favorites! Flaky sea salt on top is another game changer.
Store the bars covered, or in an airtight container, at room temperature.
No, no you do not have to share. 🙂
More Dessert Bar Recipes
If you love easy recipes, ones that include sugar specifically, you’ve gotta check these out, too!
Did you make this recipe? Please leave a star rating and review in the form below. I appreciate your feedback, and it helps others, too!
Get the Recipe Molly Beth’s Chocolate Peanut Butter Oatmeal Cookie Bars
Ingredients
- 1/2 cup butter, softened at room temperature
- 1/2 cup brown sugar
- 1/2 cup granulated sugar
- 1 egg, room temperature
- 1/2 heaping cup creamy peanut butter
- 1/2 teaspoon vanilla extract
- 1 cup all-purpose flour
- 1/2 teaspoon baking soda
- 1/4 teaspoon salt
- 1 cup old-fashioned oats, rolled oats
- 1.5 heaping cups chocolate chips*
Equipment
Instructions
- Pre-heat the oven to 350° F. Line an 8×8 pan with parchment paper.
- In a large mixing bowl, using an electric mixer, combine the butter, brown sugar, and granulated sugar. Add egg, peanut butter, vanilla extract, flour, baking soda, and salt until just combined. Stir in the oatmeal and chocolate chips.
- Spread the dough evenly in your pan. Top with additional chocolate chips as desired for looks – and, chocolate! Bake for 18-22 minutes until edges are set and begin to just turn golden brown. The middle will be slightly jiggly, but that's what you want. The bars are like cookies in that you don't want them overbaked, with a slightly gooey center. If you prefer them more well done, bake for an additional 5-7 minutes.
- Place the pan on a cooling rack and let it cool at least 15-20 minutes before serving so they have time to set up. The longer you let them cool, the more set they will be. However, they're just so so good when enjoyed warm that I often will eat them warm with a fork instead of "bar form".
- The bars are excellent served with ice cream or on their own. Store any leftovers covered at room temperature.
Notes
- I like to use milk chocolate chips in these bars, however, semi-sweet or a combination of the two are just as delicious!
- You can use a 9×9 pan, the bars just won’t be quite as thick. Reduce baking time slightly if doing so.
This post was originally FITK’s first post on March 22, 2015. The photos and text were updated in November 2019, but no changes were made to the recipe.
love this recipe! Gorgeous photos, too! I cannot wait to see what you post next!!
Congrats on your first post! Wonderful blog! I love the photography and anecdotes. This recipe looks dangerously good 😉
I enjoyed reading your blog. The way that you take time to explain the ingredients and directions makes me want to bake deserts more. Great job!
Thanks, Torchia! Let me know if you make them, they’re super easy!
Delicious recipe AND entertaining writing? Love.
So glad you enjoyed, Katie!
So yummy.
Could you double the recipe and bake it in 13×9? A 8×8 pan is definitely not enough 🙂
Haha! I totally agree it’s not enough! I’ve never tried doubling before (but now I’m questioning all my life decisions ;)) – I don’t see why that wouldn’t work though. You may just have to adjust the bake time slightly. Let me know how it works out!
What kind of oatmeal do you use? Quick oats? Steel cut?
Just regular old fashioned oats. Enjoy!
These are addicting! This is my go to recipe for a quick and easy “dish” for a potluck. Someone always ends up wanting the recipe. To add a little flare of my own, I add M&Ms.
OH! I love the idea of adding M&Ms – no one can argue with more chocolate! 🙂
I made these for a teenager Friendsgiving Get-Together. There was a dessert table FULL of yummy treats. These bars were gone instantly. I was sad to come back to an open plate.
I know excatly what you’re talking about! I’m glad everyone enjoyed them… now you deserve to make a pan just for yourself 😉 Happy Thanksgiving!
Ok I have been SO excited to make these, and I was planning to this weekend but with COVID I can’t find regular flour ? Do you think swapping equal parts almond flour would work? Thank you!
So sorry for the delay! I haven’t tried them with almond flour myself, you should be able to sub 1:1, but use your best judgement on if it seems like it needs another egg. The almond flour sometimes requires more binding agents. Although maybe a little extra peanut butter would help, too. 😉 I’d love to hear if you try it!
Delicious!! Could eat the whole batch in one day! They are a new family favorite, and are super easy to make!
I’m so glad your family enjoys them, Emma! Could definitely eat the whole batch in one day haha!
Becca, your bars are famous at our house. They are so easy to make that it’s tempting to whip up a batch whenever I have the oven on. They never last long – and are super good when still just a bit warm with a scoop of vanilla ice cream on top. I justify the calories by telling myself that they contain all the food groups – peanut butter and chocolate and ice cream are food groups, right?
Haha! Those are 100% food groups to live by in my mind! I’m so glad your family loves them, Anita! And warm with ice cream…totally the way to go! Thanks so much for commenting!
So good and so customizable! My family (of 3!) ate half and I shared the other half with the neighbors. Will keep this in the rotation! Made in an 8×8 and had to cook about 10 extra minutes. Enjoy alamode and you’ll not regret it!
So kind of you to share…it’s hard for us to not eat the whole pan too! Haha! Thanks so much for commenting, Alicia!
Very good. Easy to make . I didn’t have creamy peanut butter so I substituted chunky and was a half cup short on chocolate chips so I used 1/2 cup peanut butter chips instead. Delicious! Will definitely make again. Not as time consuming as making cookies. ♡♡
YUM! So glad to hear you enjoyed them, Cindy! Thanks for commenting!
The video includes adding baking powder but the recipe doesn’t show it. Is there baking powder in yours? Thanks!
Oh no, thank you so much for pointing this out! The recipe is correct as written in the recipe card (baking soda and salt). I’ll get the video updated ASAP. Thanks again – let me know if you have any other questions or if you try the bars!
Both boys are home and you know what that means? A double batch of Molly Beth Bars. Hope you are doing well Becca.
Ah, it sure does mean that! Enjoy!! 🙂 I hope you’re doing well, too, Anita!
I used several kinds of chips / add-ins. Really good!
Awesome! Thanks so much, Carolyn!
Soooo good. Do yourself a favor and just double the recipe. I also sprinkle mine with a little flaky sea salt cause why not.
Flaky sea salt sounds like the perfect addition! Thanks, Megan!
Wow! Just wow. These are my favorite dessert of all time, to the point that they will replace cake for my birthday this year. Love, love, love!!!
Omg best birthday dessert ever! Thanks so much, Janelle!!
Delicious 😋.
Yay! I couldn’t agree more. 🙂 Thanks so much, Consuelo!
I have been wanting something sweet but easy to make and this hit the spot. I ate a piece right out of the oven! It was a gooey delicious mess and would have been better with a glass of milk, but I didn’t have any🥲 had another piece the next day and it just wasn’t the same but still yummy! I used unsalted peanut butter and white chocolate chips as that is what I had on hand. Next time I may add some walnuts! So very good!
I’m so glad this hit the spot! I always have to reheat them the next day…they’re the best warm …and you’re right that nothing compares to them day of! I’m glad to hear you were able to use what you had on hand, too! Walnuts sound yummy!! 🙂
I made these bars yesterday for guests coming today. Big mistake! We ate 1/3 of the pan last night because they are so irresistible! Yum, yum, yum!
Haha! They don’t last long! 🙂
We did double this and used a 9×13 pan. We baked them for 20 minutes. At the point them were ever so slightly turning light brown, firmer to the touch, and had just lost that oily appearance across the top. They were just a hair dry. I think that partly because we only used 2/3 the amount of chocolate as that’s all we had on hand and I think just a minute less in the oven would have been perfect. Great flavor! We used a combination of chocolate chips and Reesie‘s peanut butter baking blend that has mini Reese‘s peanut butter cups and Reese‘s pieces in it. So good! Very rich! I look forward to making again with more chocolate and baking a hair less
Thanks so much for sharing, Julie! I’m glad to hear you enjoyed – and that Reese’s blend sounds like it would be amazing, I’m going to have to try it!
These are my favorite dessert. All my favorite things in one easy pan! I LOVED these after I had my third baby, so I always make them for friends who have a new baby. Thanks for this gem!
Yay, I’m so glad to hear! What a fabulous treat for new parents! 🙂 Thanks so much, Amanda!
This is probably the easiest cookie-bar ever. These are all my favorite cookies. The flavors melt in your mouth. Followed the recipe exactly & doubled it. First thing to hit the taste buds are chocolate chip, then transition to smooth peanut butter, and finally the oatmeal richness.
I’m so glad you love them as much as we do! Thanks so much for your review!!