Place the butter in a microwavable bowl and heat for 20-30 seconds, until the butter is melted

Add the egg and whisk with a fork

Stir in the milk, vanilla and sugar

Add the flour and salt, whisk until smooth

Divide the mixture between 2 mugs and place them in the microwave for 60 seconds. To check that the cakes are cooked, press lightly on the sponge to see it spring back. If the mixture still seems wet, place back into the microwave for about 10 seconds

Tip: make sure not to over cook, the cakes will lose their moisture :(

Add topping of your choice (i used lemon frosting and pearl sugar balls)