Make the Pretzel Crust:
Preheat the oven to 375°F. Lightly spray a 9×13-inch baking dish with non-stick cooking spray.
Crush the pretzels into small pieces using a food processor or by placing them in a large bag and using a rolling pin.
In a large bowl, combine the crushed pretzels, brown sugar, flour, and vanilla extract. Stir to combine.
Melt the butter and add it to the pretzel mixture, stirring until fully combined.
Press the pretzel mixture into an even layer in the prepared baking dish, reserving 1/2 cup for the topping.
Bake the pretzel crust for 10 minutes, then remove from the oven and let cool completely.
Make the Blueberry Topping:
In a small saucepan, combine the blueberries, sugar, lemon juice, and cornstarch. Stir to mix.
Heat over medium heat until the blueberries burst and the mixture thickens.
Remove from heat and allow the blueberry mixture to cool completely.
Make the Cream Cheese Mixture:
In a medium bowl, use an electric mixer to beat the cream cheese until smooth (about 2-3 minutes).
Add the powdered sugar and continue beating until fully combined.
Fold in the Cool Whip until just combined.
Assemble the Salad:
Once the pretzel crust has completely cooled, spread the cream cheese mixture evenly over the crust.
Spoon the blueberry pie filling over the cream cheese layer, followed by the homemade blueberry topping.
Sprinkle the reserved crushed pretzels on top for extra crunch.
Cover the dish with aluminum foil or plastic wrap and refrigerate for at least 4 hours, or overnight, to allow the flavors to meld.