Select two microwave safe mugs. In each mug place one tbsp of butter and 1 oz of semisweet chocolate. Microwave each mug for 40 seconds (microwave them separately).
Remove and stir until chocolate is completely melted with a small fork.
Add 2 tbsp sugar to each mug and stir. Beat egg in a small bowl, add half to each mug and mix.
Add in 1 tbsp flour to each cup and mix until smooth.
Cook each brownie for 1 minute in microwave (do each separately).