Using a hand mixer and a large bowl or a stand mixer fitted with paddle attachment, beat butter on high speed until completely smooth, about 1 minute.

Add the granulated sugar and brown sugar and beat together until smooth and creamy. Scrape the sides and bottom of the bowl as needed.

Next, add the vanilla extract and salt.

With the mixer on low speed, add the flour until combined. The dough will be crumbly.

Add chopped pistachios to the dough.

Turn the dough out onto a floured work surface and divide into two.

Shape divided dough into logs (about 2.5 inches in diameter), wrap in plastic wrap, and chill for at least 2 hours or overnight (recommended).

Preheat oven to 325°F and line two baking sheets with parchment paper or silicone baking mats. Set aside.

Remove cookie dough logs from the refrigerator and slice each log into 12 equally sized cookies, 24 cookies total.

Place cookies on prepared baking sheets about 2 inches apart and bake for 12-14 minutes. The cookies are ready when they are lightly golden brown around the edges. Allow cookies to cool for 5 minutes on the cookie sheets and then transfer to a wire cooling rack to cool completely.

Once the cookies are cooled, now it's time to melt the chocolate.

In a microwave-safe bowl, melt the chopped dark chocolate chunks in 15-second increments (stir after each increment) until completely melted and smooth.

Dunk the bottom of the cookie in the dark chocolate and sprinkle with sea salt. Let chocolate set and enjoy!