Step 1

In a small bowl, whisk together flour, cocoa powder, sugar, and baking powder until thoroughly, completely combined with no streaks of flour or cocoa powder remaining. Blend in milk, butter, and vanilla until batter is smooth. Pour batter into a 14-ounce (or larger) microwave-safe mug with straight sides.

Step 2

Combine peanut butter and chocolate chips and dollop into the center of the mug, gently pressing down until even with the top of the batter. Microwave on high for 1 minute. Allow to cool for a couple of minutes before serving.