All-purpose flour, sugar, cocoa powder, baking powder, salt, milk, oil or butter, vanilla extract, and optional chocolate chips.
Lightly grease the bottom of a microwave-safe mug with cooking spray or oil.
Combine flour, sugar, cocoa powder, baking powder, and salt directly in the mug.
Stir in milk, oil, and vanilla extract until smooth, scraping the bottom of the mug.
Stir in chocolate chips or sprinkle on top for a gooey finish.
Microwave on high for 70-90 seconds until the cake is set but slightly shiny.
Let rest for 1 minute, then enjoy your warm and delicious treat