Preheat your oven to 350°F. In a medium bowl, combine crushed pretzels, melted butter, and granulated sugar. Mix well until the pretzels are fully coated.
Press the pretzel mixture into the bottom of a 9x13 inch baking dish to form a crust. Bake for 10 minutes, then remove from the oven and let cool completely.
In a large mixing bowl, beat together the softened cream cheese and powdered sugar until smooth. Fold in the whipped topping until well combined.
Spread the cream cheese mixture evenly over the cooled pretzel crust. Refrigerate for at least 30 minutes to set.
In a separate bowl, dissolve the gelatin in boiling water, stirring until fully dissolved. Add the cold water and mix well.
Once the cream cheese layer has set, layer the sliced strawberries and blueberries on top. Pour the gelatin mixture over the fruit, ensuring it covers everything evenly.
Refrigerate for at least 4 hours, or until the gelatin is fully set. Cut into squares and serve chilled.