Preheat oven to 350 degrees F.

In a large bowl, beat together butter and sugar until light and fluffy. Add in eggs and vanilla, mixing well to combine. In a separate bowl, combine flour, cocoa powder, baking soda, baking powder and salt. Add half a dry ingredients to wet ingredients and mix well to combine, followed by half of buttermilk, mixing well to combine beating well after each addition. Add remaining dry ingredients, mix well, and finish with remaining buttermilk, mixing well to combine.

Line muffin pans with liners, and fill with batter, about 2/3 of the way full. Bake for approximately 15-20 minutes or until cupcakes spring back when lightly touched and/or toothpick inserted into the center comes out clean. Remove from oven and allow to cool completely prior to frosting.

With a mixer, combine softened butter and cocoa powder. Add in powdered sugar, salt, vanilla and most of your whipping cream. Beat well with mixer, adding in small amounts of remaining whipping cream, until desired consistency is reached.