- Prepare the Crust: Combine crushed biscuits with melted butter and press into a pan. Chill to set. 
- Create the Pistachio Layer: Blend ground pistachios, sugar, and heavy cream until smooth, then spread over the crust. 
- Mix the Cream Cheese Filling: Beat cream cheese, sugar, and vanilla, then spread over the pistachio layer. 
- Make the Blackberry Topping: Cook blackberries with sugar, lemon juice, and cornstarch until thickened. Cool and spread over the cream cheese layer. 
- Chill & Garnish: Let the bars set in the refrigerator, then sprinkle with chopped pistachios and fresh blackberries before serving.