Preheat oven to 375 degrees F and line 2 muffin tins with cupcake liners.
In a large bowl, mix dry ingredients (flour, sugar, cocoa powder, baking soda, and salt) by hand or with a mixer. Add eggs, buttermilk, butter, vanilla. With the mixer on low, slowly add the hot coffee.
Pour batter, which will be quite runny, into a plastic pitcher to pour from and evenly distribute between 24 cupcakes.
Bake for 20-23 minutes, or until a toothpick inserted in the center comes out clean. Let cool completely before frosting.
For the frosting: In a small saucepan on medium heat, melt butter completely. Add sugar and whipping cream, and then salt. Let it simmer for a full 3 minutes, and then remove from heat. Allow it to cool for 15 minutes, and then slowly add the icing sugar. Frost onto cooled cupcakes and decorate accordingly.