Mix crushed pretzels, margarine and 3 Tablespoons sugar together and press into a 9x13 inch pan. Bake at 400 for 8 minutes. Cool.
Mix softened cream cheese and 1 cup sugar. Fold the 2 cups thawed whipping topping into cream cheese mixture and spread over cooled pretzel crust. Dissolve strawberry gelatin in bioling water and add frozen strawberries. Chill until syrupy, then pour over the cream cheese layer and refrigerate. Cut into squares and garnish with whipped topping and a whole strawberry. Enjoy!