Double Chocolate Chip Peanut Butter Mug Cookie

Place butter in an 8 ounce coffee mug.

Melt butter in the microwave in 30 second increments.

Stir in sugars, vanilla, and baking powder.

Stir in egg yolk, cocoa, and flour.

Stir in chocolate chips.

Place peanut butter in the center and press it down slightly into the batter.

Heat mugs in the microwave for 1 minute.

Let the mugs cool slightly before eating.