½ cup + 3 tablespoons natural cocoa powder, divided
2 ½ sticks unsalted butter, divided
3 ½ cups confectioners' sugar
½ cup dark brown sugar, packed
1 tablespoon gochujang
⅓ cup roasted unsalted peanuts
Directions
Preheat the oven to 350 F.
Line a 13x18-inch sheet pan with parchment paper and coat it with cooking spray.
Add the flour and sugar to a medium mixing bowl and whisk to combine. Set it aside.
In a separate bowl, combine 2 cups of buttermilk, eggs, 1 tablespoon of vanilla, and olive oil.
Add the wet ingredients to the dry ingredients.
Sift in ½ cup cocoa powder and whisk until the batter is fully incorporated.
Pour the cake batter into the prepared pan, spreading it to the edges. Smooth the top with a spatula if needed and gently tap the tray on the counter to pop any air bubbles.
Bake the cake for approximately 25 minutes, or until a toothpick inserted in the center comes out clean. Set it aside.
Meanwhile, whisk 2 sticks of butter and 2 tablespoons of cocoa powder in a small saucepan on medium heat.
When the contents begin to bubble slightly (not boil), remove the saucepan from the heat and add ⅓ cup of buttermilk, 1 tablespoon of vanilla, and the confectioners' sugar.
Whisk until well incorporated and set aside.
In a separate small saucepan, add the remaining cocoa powder, ½ stick of butter, dark brown sugar, and gochujang over low heat.
Whisk for about 2 minutes as it comes together, then stir in the peanuts.
Working quickly, pour the icing over the warm cake and spread it evenly with a spatula.
Next, dollop the gochujang mixture across your cake, swirling with a spatula and adding smaller swirls with a toothpick.