Begin by combining 1 tsp instant coffee granules, and 2 tbsp hot water in a small bowl. Allow the coffee to dissolve while you make the icing.
Place 1 cup butter in the bowl of your stand mixer. Use the whisk of the mixer to whip the butter at medium speed.
While the butter is whipping, slowly add 3 cups of powdered sugar 1 cup at a time. Make sure to stop the mixer and scrape down the sides and bottom of the bowl until everything is incorporated.
Once all the sugar has been added, continue whipping the butter mixture on high speed for around 5 minutes. You want the mixture to be light and fluffy.
Slowly add ¾ cup cocoa powder and whip until it is completely combined.
Add 1 tsp vanilla extract. Slowly add ¼ cup of heavy cream to the icing.
Slowly drizzle the coffee into the frosting. Scrape down the sides of the bowl to ensure everything is combined
Increase the speed to high and whip the frosting for 5 minutes to get the right consistency. You want it to be light and fluffy!
Use the frosting immediately, or store it in an airtight container for up to 3 days.