Melt the butter in a small dish. Add the peanut butter and mix well. In the mug, mix together the vanilla, egg, and sugar until well combined. Combine the flour, cocoa, salt, and baking powder and add to the mug. Pour in the peanut butter/butter mixture and mix well. Stir in the chocolate chips. Put in the microwave for 1-2 minutes or until desired doneness is reached (all microwaves are different so you might have to experiment a little. I only do it for about 1 minute). Top off with vanilla ice cream and caramel sauce!