Step 1

In a small bowl, whisk together flour, sugar, baking powder, and cinnamon until thoroughly combined.

Step 2

Blend in milk, butter, and vanilla until batter is smooth.

Step 3

Into a 14-ounce (or larger) microwave-safe mug with straight sides (for even cooking), scoop a big spoonful of batter, then sprinkle with a spoonful of cinnamon sugar. Alternate layers, ending with cinnamon sugar.

Step 4

Microwave on high for 1 to 1 1/2 minutes, or until cake is done to your liking. Allow to cool for a couple of minutes before serving.