Step 1

In a microwave-safe mixing bowl, beat the softened unsalted butter (½ cup, i.e. 1 stick), vanilla extract (2 teaspoons), and salt (¼ teaspoon) on medium-high speed for 1 minute until smooth. Turn the mixer to low speed then slowly add the unsweetened cocoa powder (½ cup) and powdered sugar (2 cups). You may need to stop and scrape down the sides. Add 2 tablespoons of milk.

Step 2

Beat on high for 1-2 minutes until creamy and the frosting is at a good consistency to pipe. If it looks too runny, add more powdered sugar. If it looks too stiff, add another 1-2 tablespoons of milk until you get to the desired consistency.

Step 3

Place the mixing bowl in the microwave and heat for 15 to 30 seconds, or until glossy, easy to stir and smooth.

Step 4

Spread the frosting onto a 9x13 pan of brownies.

Step 5

Although the sugar to milk ratio makes the frosting shelf stable for 1-2 days, you may want to store your frosted brownies in the fridge for peace of mind.