Place room temperature butter in the bowl of a stand mixer or hand mixer. Beat on medium-high speed for 8 minutes, stopping halfway to scrape down the sides with a rubber spatula.
345 grams unsalted butter
Once the butter is fluffy add the powdered sugar one cup at a time, mixing on low speed. Stop to scrape down the sides and bottom of the bowl as needed.
420 grams powdered sugar
Mix in the vanilla, espresso powder, and salt on medium speed for about 2 minutes until fully combined.
1 teaspoon vanilla extract, 2 tablespoons espresso powder, ½ teaspoon salt
For cakes, reduce to low speed and mix for another minute to eliminate any air bubbles, creating a smooth and creamy buttercream. For cupcakes, increase the speed to medium-high for an airy frosting.
Spread the frosting on cake layers or add it to a piping bag for cupcakes. Enjoy!
Notes
Use espresso powder that dissolves instantly, not ground espresso beans.Storage: Store leftovers in an airtight container in the fridge for up to 1 week. Let it sit at room temperature for a bit to soften for 30 minutes before using.Freezing: Wrap the frosting in plastic wrap and place in a freezer bag. Freeze for up to 3 months. Thaw overnight in the fridge and then on the counter for 30 minutes before using.