LIne 9x13 pan with crackers. Bring butter, sugars, crumbs and milk to a high boil on medium heat. Boil 5 mins, stirring constanly. Cool slightly. Pour half of sauce over crackers and spread. Place another layer of crackers over sauce. Pour and spread the remainder of the saunce. Top with another layer of crackers.
Melt topping ingredients and spread over top layer of crackers.