Mix together pretzels, butter and sugar and spread in 9x13 pan. Bake 8-10 minutes at 400°. Beat cream cheese and sugar until creamy. Mix in 1 cool whip. Spread over cooled crust. Prepare jello using 2 cups boiling water. Combine strawberry jello with frozen strawberries. Let set in frig until slightly thickened. Pour over cream cheese. Chill. Top with other carton of cool whip. Refrigerate.