1. Prepare the Pretzel Crust:

1. Preheat oven to 350°F. Lightly spray a 7×11 baking dish with non-stick cooking spray and set aside.
2. Crush the pretzels using a food processor or by placing them in a resealable bag and crushing with a rolling pin.
3. In a large bowl, mix crushed pretzels, brown sugar, flour, and vanilla extract. Stir well.
4. Melt the butter and add it to the mixture, stirring until combined.
5. Press the mixture into the prepared baking dish, reserving ½ cup for topping.
6. Bake for 10 minutes, then let it cool completely.

2. Make the Lemon Filling:

1. In a mixing bowl, whisk together evaporated milk and instant lemon pudding mix until smooth and thickened.
2. In a separate bowl, beat cream cheese until fluffy. Add lemonade concentrate and mix until well combined.
3. Gently fold in the lemon pudding mixture, stirring until smooth.
4. Spread the lemon filling evenly over the cooled pretzel crust.

3. Prepare the Blackberry Topping:

1. In a saucepan over medium heat, add 2 cups of blackberries, sugar, lemon juice, and 5 tablespoons of water. Stir occasionally until the blackberries break down.
2. In a small bowl, whisk cornstarch and remaining 2 tablespoons of water until smooth.
3. Slowly add the cornstarch mixture to the blackberry sauce, stirring constantly. Cook until the mixture thickens.
4. Remove from heat and stir in the remaining 1 cup of blackberries for texture.
5. Let the topping cool slightly, then spread over the lemon filling.

4. Assemble & Chill:

1. Sprinkle the reserved pretzel crust mixture over the top.
2. Cover and refrigerate for at least 4 hours to allow flavors to set.
3. Slice and serve chilled. Enjoy!