For the Jell-O layer:

1. Add the Jell-O mix to a small bowl and pour in 2 cups of boiling water. Whisk until completely dissolved. Let it cool to room temperature.

For the pretzel layer:

1. Preheat the oven to 350°F (175°C).
2. Place the pretzels in a zip-top bag. Using a mallet or rolling pin, crush them into small crumbs.
3. In a small saucepan, melt the butter over medium heat. Add the sugar and stir occasionally until dissolved.
4. Remove the saucepan from heat and stir in the crushed pretzels until well combined.
5. Press the pretzel mixture into a 9×13-inch baking dish to form an even layer.
6. Bake for 10 minutes, then let it cool to room temperature.

For the cream cheese/whipped cream layer:

1. In a mixing bowl, use a hand mixer or stand mixer to beat the cream cheese and granulated sugar until fluffy (about 2 minutes).
2. Fold the Cool Whip into the cream cheese mixture until smooth, ensuring no white streaks remain.
3. Spread the cream cheese/Cool Whip mixture evenly over the cooled pretzel layer, sealing the edges to prevent the Jell-O from seeping through.
4. Refrigerate for 30 minutes to set.

Putting it all together:

1. Evenly distribute the sliced strawberries over the cream cheese layer.
2. Pour the cooled Jell-O mixture over the strawberries. If the dish is shallow, you may need to omit some of the Jell-O to avoid overflowing.
3. Cover with plastic wrap and refrigerate for 2-4 hours, or until the Jell-O is fully set.

Serve: Slice into squares and serve cold. Store any leftovers in the refrigerator.