Crack one egg into mug. Add three Tablespoons of brown sugar. Toss in 1/3 cup of flour and a tablespoon of softened butter. 3-4 Tablespoons of mini chocolate chips. Mix cake together with a spoon. Microwave your cake for 1 1/2-2 minutes, or just until the top center of the cake has set. Serve with a dollop of ice cream and enjoy!