Active Time: 45 minutes
By Esteban Castillo, Chicano Eats
Preheat your oven to 350ºF and grease and line a 9×13” baking pan with a parchment sling so the two longer sides have a piece hanging over the pan to help with lifting later. In a medium-sized bowl, whisk together the flour, baking powder, and salt and set aside. Beat the butter with the sugar in the bowl of a stand mixer fitted with the paddle attachment on medium speed until light and fluffy and paler in color, this should take about 2 minutes. Add the peanut butter and beat for 30 more seconds to incorporate.
Add the vanilla and eggs, one at a time, making sure that ones mixed in before adding the next. After the eggs have been mixed in, add one third of the dry ingredients, mix on low to incorporate, then 1/3 of the buttermilk, followed by another third of the dry mixture, another third of the buttermilk and then finally the last amount of each. Mix just until combined then use a silicone spatula to scrape down the sides of the bowl to make sure everything’s mixed in there then add the batter to the prepared pan, smooth it out, and bake for 25-30 minutes, until the cake is lightly golden brown and a toothpick or skewer inserted into the center of the cake comes out clean. Let the cake cool completely then make the buttercream.
In the bowl of a stand up mixer fitted with the paddle attachment, cream the butter with the vanilla and salt for a full minute at medium speed. Turn the speed down to low and add the powdered sugar 1/2 cup at a time, then add the ground Mexican chocolate. If you’re not able to find ground Mexican chocolate at the grocery store, simply use tablets of Mexican chocolate, break them down as much as you can, then pulse them in a blender or food processor until it is very fine.
After you have all the powdered sugar and chocolate mixed in, add the heavy cream and turn the mixer on low to incorporate it then to medium high for a full minute to make the buttercream nice and fluffy. Spread the frosting evenly over the cake and top with the sprinkles. I like to place my cake back in the fridge for 30-45 minutes and wait until the frosting firms up for a cleaner slice!