The coffee flavor in this frosting is so rich and pairs great with the salted butter and powdered sugar. It's like a sweet cup of coffee but it will include cake!
In a small dish, add in the 3 tablespoons instant coffee granules and 3 teaspoons warm water. Stir until the coffee is completely dissolved. Set aside.
In a large mixing bowl, add in the 1 cup butter. Beat with a hand mixer on medium until creamed.
Add in the coffee mixture and 3 cups powdered sugar. Beat on low until the mixture comes together.
Add 1 tablespoon of milk and beat until combine. If it still feels too thick, add the additional 1 tablespoon of milk. Beat on medium speed for 2 minutes until the frosting is light and fluffy.
Store in an airtight container at room temperature for 1 to 2 days or in the refrigerator for 7 days.
Notes
Storage: You can store the coffee frosting at room temperature for 1-2 days, or in the fridge in an airtight container for up to 7 days.Freeze: You can place the frosting in a freezer-safe container and store it in the freezer for 3 months. Once you're ready to use it, place it in the fridge overnight to thaw. Once thawed, whip the frosting with an electric mixer to fluff it back up.