01 -
Line a plate with parchment paper. Spread the pistachio cream into a thick sheet or scoop it into small dollops. Freeze for at least 1 hour until solid. If spread into a sheet, cut into squares once frozen and return to the freezer.
02 -
In a small bowl, whisk together flour, cornstarch, baking powder, baking soda, and salt. Set aside.
03 -
In a large mixing bowl, whisk together melted butter, brown sugar, and granulated sugar until smooth. Add the egg and vanilla extract, whisking until the mixture is thick and glossy.
04 -
Gradually add the dry ingredients to the wet ingredients, whisking until barely combined. Fold in the chopped chocolate and pistachios until just mixed. Using a 4-tablespoon cookie scoop, portion the dough onto a lined board. Refrigerate for about 1 hour until firm.
05 -
Preheat the oven to 350°F (175°C). Flatten each chilled dough ball, place a frozen piece of pistachio cream in the center, and seal the dough around it. Top with extra chocolate chunks, pistachios, and additional frozen cream pieces if desired.
06 -
Bake the cookies for 11-12 minutes, or until the edges are set but the centers remain soft. Immediately sprinkle with flaky salt while still warm. Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack.