Preheat your oven to 325°F.
In a mixing bowl, combine the cake mix, pudding mix, sour cream, eggs, heavy cream, espresso powder (if using), milk, and vegetable oil. Whisk until the batter is smooth, or use a stand mixer with the paddle attachment.
Gently fold in the peanut butter chips using a rubber spatula.
Grease a mini bundt pan with butter and dust lightly with flour to prevent sticking. Tap out any excess flour.
Pour the batter into each tin, filling them only about 2/3 of the way to the top.
Bake in the preheated oven for 20 to 25 minutes, or until a toothpick inserted into the center comes out clean.
While the cakes bake, prepare the frosting. In a mixing bowl, beat together the cream cheese, butter, powdered sugar, vanilla extract, and cream until smooth and creamy, about 2 minutes.
Allow the cakes to cool for 15 minutes before carefully removing them from the pan and transferring to a flat surface. If needed, repeat the baking process for any remaining batter.
Once the cakes are completely cooled, fill a piping bag with the creamy peanut butter (with the tip cut off) and another piping bag with the cream cheese frosting.
Pipe the peanut butter from the outside to the center of each cake, covering the top surface. Repeat the process with the cream cheese frosting.
Enjoy! Store any leftovers in the refrigerator for a delicious chilled treat.