This potato and egg casserole is an easy, elegant, frittata-like dish to serve at breakfast or brunch. Layers of Yukon gold potatoes, gruyere cheese, herbs, garlic, and shallot burst with flavor in this vegetarian egg bake. Top with arugula for added texture, color, and bright, peppery freshness.
Preheat the oven to 350F. Prepare the pan by spreading approximately ½ tablespoon butter on the sides and bottom of a 9-inch tart or pie pan with sides (or an 8x8 glass baking dish).
In a skillet over medium heat, melt butter and add the diced onion and shallot, with a pinch of salt. Cook for 2-3 minutes, then add the chopped garlic, red pepper flakes if using, rosemary, and thyme. Cook for an additional 2-3 minutes until tender and fragrant. Remove and let cool slightly.
2 Tablespoon unsalted butter, ½ cup yellow onion, ½ cup shallot, 3-4 cloves garlic, Pinch red pepper flakes, 1 ½ Tablespoon fresh rosemary, 1 Tablespoon fresh thyme
Meanwhile, whisk together the eggs, half-and-half, ½ tsp kosher salt, and ¼ tsp black pepper (more or less as desired). Set aside.
6 eggs, ¼ cup half-and-half, 1 ½ tsp kosher salt, ¼ tsp freshly ground black pepper
Use a mandoline to thinlyslice the potatoes. In order for them to cook through, they must be thin - about 1/16 of an inch to cook properly. If you're concerned your potatoes aren't thin enough (or you cut them by hand) then I recommend parboiling them for 2-3 minutes before layering to ensure they'll cook through.
½ pound Yukon gold potatoes (approx. 2 medium potatoes)
In the prepared baking dish, layer the very thinly sliced potatoes in an even layer on the bottom, creating a second layer as needed and continuing to layer until you've used all the potato slices. Evenly spread ⅔ of both cheeses on top of the potatoes. Reserve the rest of the cheese for the top.
3 ounces gruyere cheese*, ¼ cup parmesan cheese*
Add the cooled onion mixture into the whisked eggs. Slowly pour the eggs on top of the cheese and potatoes, allowing it to soak down into the potato layers. Place the baking dish on top of a baking sheet if there’s a risk for any liquid to spill out.
Bake for 36-40 minutes, until the edges are golden brown and the center is just set. The cook time may vary depending on the baking dish you're using; be sure to start checking it around 30 minutes.
Let the egg bake cool for 15-20 minutes before serving. Optional: toss the arugula with olive oil and a squeeze of lemon before topping. Place the arugula (dressed or not) on top, or serve it on the side. Garnish with additional freshly cracked black pepper.
2 cups arugula
Notes
Potatoes: if you're cutting the potatoes by hand and/or they are not thin enough, par-cook them in boiling water for 2-3 minutes before layering in the pan.
*Look for cheese specifically labeled vegetarian as desired. Substitute Gruyere with Jarlsberg for a vegetarian version if needed.