Mix cake and bake as directed in 9x13 pan. When it comes out of oven cover with the mini marshmallows and put back in oven for 3 minutes. Bring it out of oven and spread the marshmallows. Melt in pan or microwave in glass bowl the chocolate chips and crunchy peanut butter. Pour over the Rice Krispies. Spread over the cake and marshmallows.