Preparation Steps

• Preheat the oven to 350°F. Grease two 9-inch round cake pans, line the bottoms with parchment rounds, and lightly flour the sides.
• Bloom the cocoa: In a heatproof bowl, whisk the hot coffee into the cocoa powder until a smooth, glossy paste forms. Let stand 5 minutes to cool slightly.
• In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon until evenly combined.
• In a separate bowl, whisk the granulated sugar, brown sugar, and eggs for 45–60 seconds until slightly thickened and lighter. Whisk in the oil, vanilla, and sour cream until smooth.
• Whisk the cocoa-coffee paste into the egg mixture until uniform. Add the dry ingredients in two additions, alternating with the milk, folding gently with a spatula and stopping as soon as no dry streaks remain.
• Divide the batter evenly between the prepared pans and tap each pan firmly on the counter to release air bubbles.
• Bake 28–33 minutes, or until the centers spring back and a toothpick comes out with a few moist crumbs. Cool in pans 10 minutes, then turn out onto racks and cool completely.
• Make the frosting: In a stand mixer with the paddle (or with a hand mixer), beat the butter on medium-high until pale and fluffy, 2–3 minutes. Beat in the peanut butter for 1 minute more. Add half the powdered sugar and mix on low to combine. Add vanilla and half the cream; beat on medium until smooth. Add remaining sugar and cream, then whip 1–2 minutes until light. Adjust with a splash more cream for spreadability and a pinch of salt to balance sweetness.
• Level the cake layers if domed. For extra drama, optionally split each layer horizontally to make 4 thinner layers. Place the first layer on a board and spread an even layer of frosting (about 3/4 cup) to the edges. Repeat with remaining layer(s).
• Apply a thin crumb coat over the top and sides and chill the cake for 15 minutes to set. Finish with a thicker, smooth coat of frosting and chill 10 minutes while you prepare the ganache.
• Ganache drip: Heat the cream in a small saucepan until steaming (do not boil). Pour over the chopped chocolate and corn syrup in a bowl. Let sit 2 minutes, then stir from the center outward until silky. Cool 10–15 minutes until slightly thickened but still pourable.
• Spoon or bottle the ganache around the top edge to create drips, then spread a thin layer over the center. Pipe any remaining frosting in swirls on top and finish with chopped mini peanut butter cups. Chill 10 minutes to set before slicing.