01 -
Add the self-rising flour and granulated sugar to a 14-ounce microwave-safe mug and stir until fully combined.
02 -
Add the creamy peanut butter, whole milk, melted butter, and vanilla extract to the mug. Stir thoroughly until the batter is smooth and uniform.
03 -
Cook the mixture in the microwave for 1 minute 30 seconds to 1 minute 45 seconds, adjusting time based on your microwave's power until the cake is set.
04 -
Let the cake cool for several minutes. Optionally, top with 1 tablespoon of creamy peanut butter and spread as it melts from the residual heat.