In a mixing bowl, beat the softened butter until creamy and smooth.

Mix in the cocoa powder until fully incorporated.

Slowly add the powdered sugar, one cup at a time, mixing on low speed.

Pour in the vanilla extract and mix until well combined.

Add heavy cream or milk, one tablespoon at a time, until you reach your desired consistency.

Increase the mixer speed and beat the mixture for an additional 2-3 minutes.

Take a small taste of your buttercream and adjust sweetness or chocolate flavor if needed.

Use a spatula to frost your cakes, cupcakes, or cookies as desired.