Prep: 1. Bring butter and milk to room temperature. Make: 1. Using an electric mixer, cream butter. Sift in cocoa powder and mix on medium until well-combined. 2. Add powdered sugar and milk to cocoa mixture by adding 1 cup of sugar followed by about a tablespoon of milk. After each addition has been combined, turn mixer onto a high speed for about a minute. Repeat until all sugar and milk have been added. 3. Add vanilla extract and espresso powder and combine well.
If frosting appears too dry, add more milk, a tablespoon at a time until it reaches the right consistency. If it appears to wet and does not hold its form, add more confectioner’s sugar, a tablespoon at a time until it reaches the right consistency.