Chocolate-Peanut Butter Layer Cake

Preheat the oven to 350 degrees F (175 degrees C). Grease and flour three 8-inch cake pans.

Mix sugar, oil, sour cream, cocoa powder, eggs, vinegar, vanilla, and salt together in a mixing bowl. Add flour and water in batches, mixing and alternating between each, until incorporated. Whisk to create a smooth batter. Pour evenly into the prepared cake pans.

Bake in the preheated oven until a toothpick inserted into the center of each layer comes out clean, about 30 minutes. Cool on a wire rack for 5 minutes. Run a table knife around the edges to loosen. Invert carefully onto a serving plate or cooling rack. Let cool, about 30 minutes.

Combine cream cheese and butter for frosting in a very large mixing bowl with an electric mixer. Slowly add confectioners' sugar a few cups at a time until smooth. Mix in peanut butter to incorporate thoroughly.

Generously distribute the frosting between the layers of the cake and on the top and sides. This frosting is a bit firm and easy to work with. At this point, place the cake in the refrigerator for at least 1 hour to set; it will be extremely heavy.

Microwave chocolate, peanut butter, and corn syrup for glaze together in short 30-second intervals, mixing between each, until the chocolate is melted. Whisk in half-and-half until smooth. While warm, drizzle over the frosted cake.

Place the cake back into the refrigerator to set, about 30 minutes. Remove the cake from the refrigerator 30 minutes to 1 hour before serving.