see: yellow cake. also, prepare to give these beaters a full mouth-over — this is the absolute perfect basic chocolate frosting recipe, totally (and easily) customizable to suit your taste and preferences.
– butter (softened, 1 cup)
– confectioner’s sugar (3 1/2 cups)
– cocoa powder (½ cup)
– sea salt (½ teaspoon)
– vanilla extract (2 tablespoons)
– milk (all substitutions work, 4 tablespoons)
cream the butter for a few minutes in a stand mixer or with a pair of beaters. then, with beaters off, sift powdered sugar and cocoa powder together into the bowl — fold together with a spatula to wet ingredients, and when you’re safely past dust-explosion stage, turn the beaters / mixer back on. add remaining ingredients and beat for three or so minutes, and you’re done with your base.
when you’re done frosting the cake, there’s no need to refrigerate it, unless you like cold cake. just cover with plastic wrap or similar to keep things fresh. there’s no difference between this frosting being out of refrigeration and a butter dish that lives on your countertop.
this is the fun part — tasting time! in small increments, about a scant quarter cup at a time, you can push the frosting to a more cocoa-like flavor or to a more sugary flavor, simply by increasing either ingredient. if you need to thin the frosting out at any point, just add milk (or your milk-equivalent) one tablespoon at a time.
on top of the basic flavor profile, you can also experiment with things like a hint of orange zest, or dissolving instant espresso in the milk, or adding a pinch of cinnamon.