In a medium-sized microwave safe bowl, melt the butter if you haven't already. Then add the rest of the ingredients and stir to combine thoroughly. Spoon the batter into 2 mugs, or 4 small paper baking cups. Microwave for 1 minute on high if using the baking cups, 1 minute and 30 seconds if cooking both mugs. Check for doneness and if still liquid in the center microwave for 15 second increments until just set. Serve warm. Ice cream and toppings are optional and not included in nutrition info below.