For the cake
10 tablespoons butter, softened (plus additional butter for pan)
1 cup sugar
1-3/4 cups flour
3/4 teaspoon baking powder
3/4 teaspoon baking soda
1/3 cup cocoa powder
1-1/4 cups buttermilk
1/3 cup peanut butter chips
For the flan
1 (12-ounce) can evaporated milk
1 (14-ounce) can sweetened condensed milk
4 ounces cream cheese, softened to room temperature
1 tablespoon vanilla extract
1/3 cup peanut butter, melted
1/3 cup prepared fudge sauce, warmed
1/4 cup chopped peanuts
1. Preheat oven to 350 degrees F.
2. Rub the inside of a 12-cup bundt pan with butter to prevent sticking.
3. To prepare the cake: Using an electric mixer, beat the butter and sugar together until light and fluffy. Add the egg and beat for another minute. In a separate bowl, combine the flour, baking powder, baking soda and cocoa powder. Beat a third of the flour mixture into the butter mixture, followed by half of the buttermilk, followed by another third of the flour mixture, then the remaining buttermilk, and ending with the remaining flour mixture. Stir in the peanut butter chips. Spread the cake mixture in an even layer on the bottom of the prepared bundt pan.
4. To prepare the flan: Combine all flan ingredients in a blender and blend until well-combined. Pour the flan mixture over the cake batter. (Don’t worry if the cake batter mixes a bit with the flan. They will separate during baking.)
5. Cover the bundt pan with foil. Place the bundt pan inside a larger roasting pan or large skillet. Carefully fill the roasting pan or skillet with about an inch or so of hot water. (The hot water bath will help the flan custard to cook gently.)
6. Place the pan on the middle oven rack and bake for about 90 minutes*, until the top of the cake is firm and a toothpick inserted comes out clean. Carefully remove the pan from the oven, remove the bundt pan from the water bath, and cool for at least an hour at room temperature. Then, give the bundt pan a little jiggle to ensure the cake and flan are loosened. Place a large serving plate over the top and invert the cake onto the serving plate. Refrigerate for several hours before serving.
7. To garnish, drizzle the top of the cake with the melted fudge sauce and peanut butter. Sprinkle with the chopped peanuts.
*The original recipe calls for a cooking length of one hour, but it actually takes a good 90 minutes, as I’ve noted in my adaptation of the recipe.