In a bowl, combine the pretzels, butter and sugar. Press into an ungreased 13x9-in. baking dish. Bake at 350° for 10 minutes. Cool on a wire rack. , For filling, in a small bowl, beat whipped topping, cream cheese and sugar until smooth. Spread over pretzel crust. Refrigerate until chilled. , For topping, dissolve gelatin in boiling water in a large bowl. Stir in sweetened strawberries; chill until partially set. Carefully spoon over filling. Chill until firm, 4-6 hours. Cut into squares; if desired, serve with additional whipped topping and pretzels.