Line bottom of 9" x 13" baking dish with soda crackers. Prepare pudding mix according to package instructions. Gently pour thin layer of pudding over crackers and spread evenly. Stir the jam to make it smooth, then carefully spread a thin layer of jam over pudding. Repeat same three layers once more, then top with layer of crackers and layer of pudding. Spread Cool Whip over top of entire dish and sprinkle with your favourite topping. Cover dish with plastic wrap and refrigerate for at least 6 hours or overnight, to give the soda crackers time to transform into flaky pastry.