Beat the sugar and cocoa powder to incorporate the vegan butter coffee and vanilla. If you need more liquid, add a small amount at a time. Beat for two minutes or so until smooth. If you need to stiffen the frosting, add a little more confectioner's sugar.
Chill the frosting before using it. I chill it, covered, for roughly an hour. Frost the cupcakes. Cover in an air-tight container until serving. If making ahead of time, chill frosted cakes briefly in the freezer before wrapping individually and freezing.