Preheat oven to 350°F.
Using a stand mixer or a handheld electric mixer, cream together butter and sugar.
Add melted chocolate, oil, eggs, vanilla, coffee, and heavy cream and mix again just until smooth.
In a separate bowl, mix together all dry ingredients (flour, baking soda, baking powder, cocoa, and salt).
With the mixer turning at low speed, slowly add the dry ingredients to the wet.
In a greased or lined cupcake pan, spoon batter into each cup, filling only halfway.
Add 1 teaspoon of peanut butter to each cup and swirl into the batter, using a chopstick or butter knife.
Bake for 18-20 minutes or until a toothpick inserted in the center comes out mostly clean.