Preheat oven to 400 degrees F. In a medium bowl, stir together the pretzel crumbs and sugar. Pour the melted butter over top and stir with a fork until all of the crumbs are evenly moistened. Press into the bottom of a 9x13-inch baking pan. Bake for 10 min, then cool completely.
Using an electric mixer, beat the cream cheese and sugar on medium speed until light and fluffy, about 3 minutes. Using a rubber spatula, gently fold in the Cool Whip. Spread evenly over the crust and refrigerate while you prepare the topping.
Place the dry Jello in a large bowl and add the boiling water. Stir for at least 2 minutes, until the gelatin is completely dissolved. Stir in the cold water. Refrigerate for 1½ hours or until slightly thickened (will the consistency of egg whites). Stir in the strawberries and pour over the cream cheese layer. Refrigerate for at least 3 hours, or until the Jello layer is set. Cut into squares to serve. Leftovers should be stored, covered, in the refrigerator for up to 3 days.
Pretzels: For this recipe, I suggest using small pretzel twists or sticks. They will be easier to measure and crush.
Cool Whip: I do not recommend substituting fresh whipped cream, as it's not as stable and can cause the filling to weep and create a soggy crust.
Recipe Variations: See the post above for ideas on different fruit/Jello combinations.
Serving: Serve plain or with a dollop of whipped cream!
Storing: Keep covered in the refrigerator for up to 3 days.
Make-ahead: This recipe is the ideal make-ahead dessert. Since it requires a minimum of 3 hours to set I would recommend making it the day before you plan to serve it.