In a large mug melt the butter in the microwave for 15-30 seconds

Add sugar and stir, add the egg and vanilla essence then whisk

Add flour, baking powder and salt to the mug, stir, add the chocolate chips and stir

Put the mug in the microwave and cook for 1-2 minutes or until when a toothpick inserted in the center comes out clean

Serve hot with a drink of your choice