1. Line a 9-by-13-inch baking pan with foil, leaving a 2-inch overhang over both long sides. Mist with cooking spray. In a large bowl, mix cracker crumbs, sugar and butter. Press evenly into bottom of baking pan and refrigerate until firm, about 30 minutes.
2. Preheat oven to 350ºF. Sprinkle nuts, coconut, chocolate chips and malt-ball pieces evenly over crust. Drizzle condensed milk over. Bake until edges are golden, 25 to 30 minutes. Let cool completely in pan on a wire rack. Use foil overhang to remove from pan. Peel off foil, cut into bars and serve.