2 ¼ sticks butter cut into ½ in pieces, room temperature if using a hand held mixer

½ c sugar

¼ brown sugar

1 tsp vanilla extract

2 ½ c flour

6 ounces bittersweet dark chocolate coursely chopped

1 large egg beaten

Demerara sugar for rolling

Flaky sea salt for sprinkling

Line two rimmed baking sheets with parchment paper. Using a stand mixer with paddle attachment, or electric hand mixer, beat the butter, both sugars, and vanilla on medium-high till it’s super light and fluffy (3 to 8 minutes, depending). Using a spatula, scrape down the sides of the bowl and, with the mixer on low, slowly add the flour, followed by the chocolate chunks, and mix, just to blend. If necessary, knead the dough with your hands to make sure the flour is totally incorporated. At this point, the dough should be smooth and feel like play-dough with no pockets of flour.

Divide the dough in half, placing each half on a large piece of plastic wrap. Fold the plastic over so that it covers the dough to protect your hands from getting sticky. Using your hands, form the dough into a log shape; rolling it on the counter will help you smooth it out, but don’t worry about getting it perfect. You can also do this using parchment paper, if you prefer, but plastic wrap is easier when it comes to shaping the log. Each half should form a 6-inch log, 2 to 2 ¼ inches in diameter. Chill until totally firm, about 2 hours.

Heat the oven to 350 degrees. Brush the outside of the logs with the beaten egg and roll them in the demerara sugar (for the crisp edges).

Using a serrated knife, carefully slice each log into ½ inch thick rounds (if you hit a chocolate chuck, slowly saw back and forth through the chocolate). If the cookies break or fall apart, just press them back together - the dough is quite forgiving. Place the on the prepared baking sheets about 1 inch apart. Sprinkle with flaky salt. Bake until the edges are just beginning to brown, 12 to 15 minutes. Let cool slightly before eating them all.

Notes: Makes 2 dozen cookiess. Cookie dough can be made ahead and stored, tightly wrapped in plastic, up to 1 week in the refrigerator, or 1 month in the freezer. Baked cookies can be stored in airtight containers for 5 days.