Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans.
In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In another bowl, whisk together the eggs, buttermilk, vegetable oil, coffee, and peppermint extract until well blended.
Gradually add the wet mixture to the dry ingredients, stirring until just combined.
Divide the batter evenly between the prepared cake pans, smoothing the tops.
Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.
Remove the cakes from the oven and let them cool in the pans for 10 minutes before transferring to a wire rack.
While the cakes cool, prepare the frosting by beating the softened butter until creamy, then gradually add powdered sugar and blend well.
Finally, add a splash of milk or cream to achieve the desired spreading consistency, then mix in a teaspoon of peppermint extract for added flavor.
Once the cakes are completely cool, frost the top of one layer, place the second on top, and frost the top and sides.
Decorate with crushed peppermint candies and optional cocoa dusting for a festive touch.