In a saucepan over medium heat, melt 1 stick of butter, stirring constantly until it quiets down and becomes frothy. Once it reaches a rich amber color and releases a nutty aroma, remove it from heat. Pour the melted butter into a heatproof bowl and immediately add the cold butter slices. Let it rest until the cold butter melts into the browned butter, stirring occasionally until well combined.

Transfer the butter mixture to a large mixing bowl or the bowl of a stand mixer. Cream together the melted butter, light brown sugar, and granulated sugar until the mixture turns light and fluffy, about 1-2 minutes.

Add the egg and beat for 30 seconds. Scrape down the sides of the bowl, then add the egg yolk and vanilla extract. Beat for an additional 30 seconds.

In a separate bowl, whisk together the all-purpose flour, baking soda, and sea salt.

Gradually add the dry ingredients to the wet mixture, mixing until just combined. Be cautious not to overmix.

Gently fold in the chopped dark chocolate chunks and salted pistachios, ensuring they're evenly distributed throughout the dough.

Using a cookie scoop, form the dough into 1/2 cup-sized balls. Refrigerate the dough for at least 1 hour or overnight.

Bake at 350 degrees for 12-14 minutes or until the edges turn lightly golden.

Once baked, remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Enjoy these delightful pistachio dark chocolate chunk cookies with a glass of milk or your preferred hot beverage!