Grab your mug: Use a microwave-safe mug that holds at least 8 oz. Please ensure it is clean and ready, as greasing is not necessary.
Mix wet ingredients: In the mug, stir together the vegetable oil, brown sugar, and egg white until smooth. Then add the peanut butter and mix again until well blended.
Add dry ingredients: Sprinkle in the flour and baking powder. Stir until everything comes together. Don’t overmix—just make sure there are no dry spots.
Toss in the chocolate chips: Fold in the chocolate chips gently. They’ll melt into the cake and give those perfect little chocolatey bites.
Microwave it: Microwave on high for about 60–75 seconds. Start checking at the 60-second mark. The cake should be puffed up but still moist in the center.
Cool and enjoy: Let it cool for a minute or two—trust me, it’s hot! Grab a spoon and dig right in.