Preheat the oven to 350°F (175°C) and line a muffin tin with cupcake liners.

In a mixing bowl, cream together the softened butter and sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

Stir in the buttermilk, bourbon, and vanilla extract until combined.

In another bowl, whisk together the flour, baking powder, baking soda, and salt.

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

Fold in the chopped mint leaves.

Divide the batter evenly among the cupcake liners and bake for 20-25 minutes, or until a toothpick comes out clean.

Allow the cupcakes to cool completely before frosting.

In a mixing bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the heavy cream, vanilla extract, mint extract, and chopped mint leaves, and beat until fluffy.

Frost the cooled cupcakes with the mint frosting.