Heat the oven to 350°F and line a 12-cup muffin pan with paper liners.
Beat the butter and sugar until light and fluffy. Beat in the eggs one at a time, then mix in the vanilla.
Whisk the flour, cocoa powder, baking soda, and salt in a separate bowl. Add the dry mixture to the butter mixture in three additions, alternating with the buttermilk, and mix just until combined.
Divide the batter among the liners, filling each about two-thirds full. Bake for 18 to 20 minutes, until the tops spring back and a toothpick comes out with a few moist crumbs.
Cool the cupcakes in the pan for 5 minutes, then transfer them to a rack to cool completely.
Beat the cream cheese and butter until smooth. Gradually beat in the confectioners’ sugar and vanilla, adding milk only if needed for a spreadable texture. Tint the frosting orange.
Pipe or spread the frosting over the cooled cupcakes and decorate as desired.