2 - 3 cups frozen raspberries (you can also use fresh
First Layer - combine broken pretzels, melted margarine and 3 tablespoons sugar. Stir until well blended. Press in 9 x 13 pan and bake at 350 degrees for 7 minutes. Cool completely.
Second Layer - Beat 1 cup sugar and cream cheese until smooth. Fold in Cool Whip. Spread over pretzel layer. Be sure to seal the cream cheese layer against the sides of the pan so that the jello mixture (3rd layer) will not be able to leak through when added.
Third Layer - Mix Jello and boiling water until jello is dissolved. Add frozen raspberries. Cool and set slightly. Pour over cream cheese layer. Refrigerate until firm.