Preheat the oven to 350°F (175°C).
In a mixing bowl, combine crushed pretzels, melted butter, and granulated sugar. Mix until well combined.
Pour the pretzel mixture into the baking dish and press it down firmly to create an even layer. Bake in the preheated oven for about 10 minutes, then let it cool completely.
In a separate bowl, beat the softened cream cheese with an electric mixer until smooth. Gradually add powdered sugar and continue to beat until incorporated.
Fold in the whipped topping until the filling is light and fluffy.
Spread the cream cheese mixture evenly over the cooled pretzel crust.
In another bowl, dissolve the strawberry Jell-O in boiling water. Stir in the sliced strawberries and let the mixture cool slightly.
Carefully pour the strawberry mixture over the cream cheese layer in the baking dish.
Refrigerate for at least 2-3 hours or until set.
Slice into squares and serve chilled.