Preheat your oven to 350 F. Line a muffin tin with cupcake liners.

Unwrap your Reese cups.

In a medium bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.

In a larger bowl, whisk the granulated sugar and brown sugar with the eggs, then add milk, oil, and vanilla until smooth.

Pour the dry mixture into the wet mixture and stir until there are no streaks of flour. Then slowly add the hot coffee or hot water.

Fill each cupcake liner about halfway with batter and drop a mini Reese cup into the center. Cover the Reese cup with more batter until the liner is about two thirds full.

Bake for about 16 to 20 minutes. They are done when the tops spring back lightly and a toothpick comes out mostly clean.

Let the cupcakes cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

Beat together softened butter and peanut butter until fluffy. Gradually add powdered sugar and a splash of cream or milk until it's smooth and pipeable.

Frost the cooled cupcakes as desired.