Freeze the Pistachio Spread:
Line a plate with parchment paper. Pour the pistachio spread onto the surface and spread it into a thick, even layer. If your spread is already quite thick, you can simply scoop out small portions using a spoon to form dollops. Place in the freezer for at least 1 hour or overnight until completely solid. If you used the sheet method, once frozen, cut it into squares using a sharp knife and return the pieces to the freezer until you're ready to use them.
Prepare for Chilling:
Line a cutting board or plate with parchment paper—this will be used for chilling the cookie dough later. Set it aside.
Mix the Dry Ingredients:
In a small mixing bowl, combine the flour, cornstarch, baking powder, baking soda, and salt. Stir well and set aside.
Make the Butter Mixture:
In a large bowl, whisk together the melted and cooled butter, brown sugar, and granulated sugar until smooth. Add the egg and vanilla extract and continue whisking until the mixture is thick and creamy.
Combine Wet and Dry Ingredients:
Add the flour mixture to the butter mixture and mix until the dough is just starting to come together—some visible flour streaks are okay at this stage.
Add Chocolate and Pistachios:
Add in the roughly chopped chocolate and pistachios. Switch to a spatula and gently fold them into the dough until everything is just combined and evenly distributed.
Scoop the Dough:
Using a large cookie scoop (about 4 tablespoons), portion out the cookie dough and place each scoop onto the prepared parchment-lined board. Chill the scooped dough in the refrigerator for about 1 hour, or until firm to the touch.
Get Ready to Bake:
Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Stuff the Cookies:
Take a chilled dough ball and flatten it gently with your fingers to form a disk. Place a frozen portion of pistachio spread (either a few squares or one dollop, depending on size and thickness) in the center. Fold the dough around the filling and pinch the edges to fully enclose the pistachio cream inside.
Top the Cookies:
Arrange the stuffed cookie dough balls on your lined baking sheet, leaving about 2 inches of space between each one to allow for spreading. Gently press a few extra chocolate chunks, chopped pistachios, and frozen pistachio cream pieces onto the tops of each dough ball for extra flavor and a beautiful finish.
Bake the Cookies:
Bake for 11–12 minutes, or until the edges are set but the centers are still soft. Immediately after removing from the oven, sprinkle the tops with flaky salt. Let the cookies sit on the baking sheet for 5 minutes before serving. Enjoy them warm for gooey centers, or let them cool to allow the pistachio filling to firm up.
