Pre-heat oven to 350°F and grease or line an 8x8 baking dish with parchment paper.
Melt butter and chocolate chips in microwave or double boiler. If microwaving, melt in 25-second increments, stirring in between, for approximately 1 - 1 1/2 minutes. Pour into mixing bowl if double broiling and set aside to cool slightly. Meanwhile, stir together flour, cocoa powder, and salt.
Whisk the sugar into melted chocolate. Add eggs one at a time, whisking between each addition. Stir in vanilla extract. Fold in the dry ingredients.
Bake for 35-40 minutes until edges are set and center doesn't jiggle. A toothpick should come out with moist crumbs to ensure you'll have fudgy brownies! Let brownies cool completely before frosting.
FROSTING:
Cream together the room temperature cream cheese and butter using an electric mixer. Add the milk, vanilla extract, peppermint extract. Add powdered sugar 1 cup at a time, fully incorporating between each addition. Add food coloring until desired color is reached, if using. Spread the frosting on cooled brownies.
DRIZZLE:
Melt chocolate chips and vegetable oil in the microwave, checking them every 15 seconds and stirring until melted completely. Drizzle over frosted brownies.
Notes
Original Frosting Recipe: 3 oz. cream cheese, 1/4 cup unsalted butter, 3 TBSP milk, 1/4 tsp vanilla extract, 3/4 tsp peppermint extract, 4 cups powdered sugar. The recipe was updated above to reduce the amount.
Store brownies in the fridge covered or in an airtight container.