Melt the butter in a medium, light-colored saucepan over medium heat. Stir or whisk constantly as it foams, then turns golden brown and fragrant, about 5–8 minutes. Immediately scrape the browned butter into a large bowl. Refrigerate for about 20 minutes, stirring occasionally, until slightly cooled but still liquid.

In the bowl of a stand mixer fitted with the paddle attachment (or a large bowl using a hand mixer), combine the dark brown sugar and granulated sugar. Pour the cooled brown butter over the sugars and beat until light and fluffy, about 2 minutes. Add the eggs and vanilla; increase the mixer speed to medium-high and beat until the mixture lightens in color and thickens slightly, about 1 minute. Reduce the mixer speed to low and mix in the baking soda and salt. Add the flour and mix just until combined. Gently fold in the chocolate chips.

Cover the dough tightly and chill for at least 2 hours or up to 48 hours. (You can chill the dough whole and scoop later, or scoop into balls first and then chill.) If scooping now, scoop the dough into 4-tablespoon portions (about 2.3-2.5 oz or ¼ cup each): cover and chill.

While the cookie dough is chilling, prepare the filling.

Melt the butter in a large, high-sided skillet over medium heat. Add the kataifi and cook, stirring often, until golden brown and crispy, about 10 minutes. Transfer to a bowl and let cool completely.

Once cooled, stir the pistachio cream, tahini, and salt into the toasted kataifi until evenly combined.

Line a small baking sheet with parchment paper. Scoop the filling into 1-tablespoon portions and place them spaced apart on the prepared
sheet. Freeze for about 1 hour, or until firm. Keep the filling in the freezer
until the cookie dough is fully chilled.

Place an oven rack in the center of the oven and preheat to 375°F. Line a light-colored baking sheet with parchment paper.

Remove the cookie dough from the refrigerator. If needed, let it sit at room temperature just until soft enough to scoop. Working with one cookie dough ball at a time, gently flatten it into a thick disc. Place a frozen pistachio–kataifi ball in the center, then wrap the dough up and around the filling, pinching to seal. Roll gently between your palms to form a smooth, tight cookie dough ball. Be sure the filling is completely enclosed so it doesn’t leak during baking.

Place the dough balls on the prepared baking sheet, spacing them about 3 inches apart. Top with chopped pistachios.

Bake until the edges are set and lightly golden while the centers remain soft, about 10-12 minutes. If desired, press a few extra chocolate chips onto the tops and sprinkle lightly with flaky sea salt. If the cookies spread unevenly, use the side of a fork or a round biscuit/cookie cutter to gently nudge them into a more circular shape as soon as you take them out of the oven.

Let the cookies cool on the baking sheet for 10 minutes, then transfer to a wire rack to cool completely. Repeat with the remaining dough, using a cooled baking sheet lined with fresh parchment.

Store leftover cookies in an airtight container at room temperature for up to 3 days.