Step 1

In a microwave-safe mug, add butter and heat in microwave until completely melted. Only heat a few seconds at a time, swirling in between, so that the butter does not overheat and splatter.

Step 2

Once butter is melted, add in pumpkin puree and then egg. Whisk vigorously until batter is smooth and no egg streaks remain.

Step 3

Add in remaining ingredients. Whisk until batter is smooth.

Step 4

Cook cake at full power in the microwave for about 1 minute 45 seconds to 2 minutes, or until cake is cooked. Let cake cool a few minutes before adding toppings of your choice and serving.