From 6 Bittersweets
Makes enough to frost at least 2 dozen cupcakes
2 cups unsweetened cocoa powder
4 to 5 cups powdered sugar
Large pinch salt
1 1/2 cups (3 sticks) unsalted butter, softened
5 to 8 Tbsp milk, half and half, OR heavy cream
1 Tbsp pure vanilla extract
Sift the cocoa powder, powdered sugar, and salt into a large bowl. In another large mixing bowl, cream the butter using an electric mixer. Alternate adding the sifted mixture (1 cup at a time) with adding the cream, mixing well between each addition. Once all the powdered mixture and 5 tablespoons of the milk have been incorporated into the frosting, turn the speed up to high and continue beating until a light, fluffy texture is achieved, at least 2 minutes. [Since the frosting will significantly lighten in color as it's beaten, you will need to scrape the sides of the mixing bowl carefully to ensure the darker portions are mixed in to make a uniformly colored frosting. Add more cream or powdered sugar if you want to thin or thicken the frosting.
Use finished frosting right away to frost cooled cupcakes or cakes. If not using right away, frosting can be covered and stored at cool room temperature for at least 2 days. However, you may need to re-beat the frosting briefly if it's been sitting a long time.