Melt butter with brown sugar. Bring to full boil and boil for 5 minutes. Line jelly roll pan with foil. Spray with non-stick spray. Place saltines on bottom of pan. When butter mixture is done boiling, carefully pour over saltines. Place in 400 degree oven for 5 minutes. Remove from oven and pour chocolate chips over top. Let melt for 5 minutes. spread with knife. Let cool completely. Break into bite-sized pieces.