Beat all the ingredients together with a whisk then pour into a mug
microwave the mixture on high for 90 seconds (all microwaves are different so adjust the cooking time according to your microwave oven)
Let the cake cool and top with sweetened whipped cream and a sprinkle of pumpkin spice blend to garnish. If you top the cake with whipped cream while it's still warm the cream will begin to melt. It will still be absolutely delicious with the melty cream running down.