In a microwave-safe mug, stir together the flour, cocoa powder, sugar, baking powder, salt, and chocolate chips with a fork, making sure to break up any clumps of cocoa. Add in the milk and vegetable oil and stir until the mixture is smooth.
Dollop the peanut butter right in the middle of the batter and poke it down a bit so that it is mostly or totally submerged.
Microwave the cake on high for one to one and a half minutes or until the cake is puffy and baked then serve warm topped with a sprinkling of icing sugar and chopped peanuts.
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