01 -
Mix the flour, sugar, salt, cinnamon, and nutmeg in a microwave-safe mug.
02 -
Stir in the melted butter, milk, and dark rum (if using) until smooth.
03 -
Microwave for approximately 90 seconds or until the cake is set. Ensure not to overcook.
04 -
Dust with additional cinnamon and serve immediately while warm.