Make the cake batter

• Mix the flour, sugar, baking powder, milk, melted butter and vanilla in a small bowl until smooth.

Make the cinnamon swirl

• Mix the melted butter, light brown sugar and cinnamon into a swirl paste.

Layer the mug

• Pour half the batter into a large mug.
• Add half the cinnamon swirl mix.
• Pour the rest of the batter on top and smooth out.
• Pipe the remaining cinnamon mix over the surface.

Add the cinnamon sugar topping

• Mix the sugar and cinnamon and sprinkle it all over the cake.

Microwave

• Microwave until there is no wet batter left, watching closely so the cake does not overflow.