Creating these scrumptious Blackberry Pistachio Dream Bars can be quite simple if you follow these straightforward steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line an 8×8-inch baking dish with parchment paper.

2. Prepare the Crust: In a mixing bowl, cream together the softened butter and granulated sugar. Add the flour and salt, mixing until a crumbly dough forms.

3. Press the Dough: Transfer the dough into the prepared baking dish. Press it evenly into the bottom of the dish to create a crust.

4. Bake the Crust: Bake in the preheated oven for 15 minutes or until lightly golden.

5. Prepare the Filling: In another bowl, combine the blackberries, chopped pistachios, cornstarch, vanilla extract, and lemon juice if desired. Gently stir to combine.

6. Mix the Eggs: In a separate bowl, whisk the eggs until well combined. Slowly add them to the berry mixture, stirring until smooth.

7. Pour Over the Crust: Once the crust is done baking, remove it from the oven and pour the blackberry mixture over it, spreading it evenly.

8. Bake Again: Return to the oven and bake for an additional 30-35 minutes until the filling is set and slightly bubbly.

9. Cool: Remove from the oven and let it cool in the baking dish for about 15-20 minutes. Then, transfer to the refrigerator to cool completely.

10. Cut and Serve: Once cooled, cut into bars and dust with powdered sugar if desired.

These step-by-step instructions will guide you effortlessly to create these wonderful bars in your kitchen.