Try making this easy Microwave Mug Brownie! It's a deliciously chocolate, gooey, and rich single-serve brownie that can be made in less than 2 minutes. Perfect sweet treat in a hurry.
Carefully remove the brownie from the microwave and allow it to sit for 1 to 2 minutes before serving. Serve warm and top with chopped walnuts and chocolate chips if you prefer.