Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners.

In a large bowl, cream together the unsalted butter and granulated sugar until light and fluffy. Add eggs one at a time, mixing well after each addition. Stir in vanilla, instant espresso powder, and brewed espresso until smooth.

In another bowl, whisk together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the wet mixture, mixing just until combined.

Spoon the batter into the muffin tin, filling each cup two-thirds full. Bake for 16-18 minutes. Cool for 5 minutes in the tin before transferring to a wire rack.

For the frosting, beat the softened butter until creamy, then gradually add powdered sugar. Mix in instant espresso powder and brewed espresso until fluffy.

Frost cooled cupcakes using a piping bag and garnish as desired.