Ingredients

2 cups (4 sticks) salted butter, at room temperature

1 cup unsweetened cocoa powder (preferably Dutch-process), sifted

1/2 tsp. instant espresso powder

5 cups powdered sugar, sifted, plus more as needed

3/4 cup heavy cream, plus more as needed

1 Tbsp. vanilla extract

1/4 tsp. kosher salt

Directions

1 In a stand mixer fitted with the paddle attachment, beat the butter on medium-high speed until creamy and lightened in color, about 5 minutes, scraping down the sides of the bowl as necessary.

2 Add the cocoa powder, espresso powder, half of the powdered sugar, and half of the cream to the bowl. Beat on low speed until incorporated, then add the remaining powdered sugar, remaining cream, vanilla, and salt. Beat on low until just mixed through, then increase the speed to medium-high and beat until the frosting is fluffy and has lightened in color, 3 minutes. Scrape down the sides and bottom of the bowl, being sure to catch any rogue powdered sugar or cocoa, and mix on low speed for about 1 minute more. If the frosting seems thicker than you’d like, you can thin it out by adding extra cream, 1 tablespoon at a time. If it seems thinner than you’d like, add extra powdered sugar, ¼ cup at a time.

3 The buttercream can be used immediately, or covered tightly and stored at cool room temperature for up to 48 hours (I like to press a piece of plastic wrap right on the surface of the buttercream to prevent crusting). It will keep, refrigerated, for up to 2 weeks, and frozen for up to 3 months. If chilled, bring the buttercream to room temperature and give it a good stir before using, adding a splash of cream if necessary, to bring it back to a fluffy, smooth consistency.