Mix the flour, melted butter and crushed pretzels together and put in a 13x9x2 pan. Bake at 350°F for 15-20 minutes. Cool.
Mix cream cheese, sugar and 4 oz. of Cool Whip together. Spread over cooled crust. Mix the puddings, and milk together. Spread over cream cheese mixture. Top with remaining (4 oz.) Cool Whip. Grate chocolate bar over Cool Whip.