Chocolate Coffee Buttercream Icing

¾ cup butter, softened

1 (4 ounce) package cream cheese, softened

1 ½ (16 ounce) packages confectioners sugar, or more as needed

¼ cup unsweetened cocoa powder

3 tablespoons strong brewed coffee, or more to taste

½ teaspoon salt

Beat butter and cream cheese together in a bowl with an electric hand mixer until creamy; slowly beat in confectioners sugar, cocoa powder, coffee, and salt until smooth and spreadable.