Put butter and chocolate in a glass bowl. Microwave for 1 minute on high. Stir until melted.
In another bowl, whisk together sugar and next 4ingredients. Whisk in chocolate mixture. Divide among 4 (10 oz) mugs.
Place mugs in microwave for 3 minutes on highest setting. Let cool 30 secs. Top with whipped cream.
Go to Full Version of