Gather all your ingredients and ensure the unsalted butter is at room temperature.
In a mixing bowl, beat the room temperature butter with your mixer on medium speed until it’s light and fluffy, about 2-3 minutes.
Gradually add the sifted cocoa powder to the creamed butter. Beat on low speed to avoid a cocoa cloud. Once incorporated, increase the speed to medium until fully combined.
Add the sifted powdered sugar, one cup at a time, mixing on low speed. Scrape down the sides of the bowl as needed.
Pour in the half & half, vanilla extract, espresso powder, and kosher salt. Beat on medium speed until smooth and creamy. Adjust thickness with more half & half if necessary.
Taste your buttercream and adjust flavors as necessary. Add more cocoa for richness or a pinch of salt to reduce sweetness.
Give the buttercream a final whip on high speed for about 30 seconds to enhance fluffiness.
