Cover bottom of cookie sheet with crackers. Put 1 cup butter and 1 cup brown sugar in a medium saucepan and bring to a boil. Boil for 10 minutes. Pour over crackers. Bake 5 minutes at 375 degrees. Remove from oven and cool slightly. Sprinkle with 1 bag of milk chocolate chips. Let them melt and spread. After chocolate sets, remove from pan and break into pieces.