Melt butter in a large, microwave safe mug.

Add the brown sugar, milk and vanilla and mix until the sugar is dissolved.

Gradually stir in flour, salt and baking powder. Stir until it's well blended.

Add the butterscotch chips and microwave for 1 minute and 20 seconds. If the batter looks a bit undercooked microwave for an additional 30 seconds until cooked. Then as it's piping hot add the chocolate chips, ice cream and the caramel sauce.