Using a stand or handheld mixer, cream the butter with the granulated and brown sugars and vanilla. If using a stand mixer, about 3 minutes results in about the right level of fluffiness. If you’re using a hand mixer, Alison Roman recommends mixing a little longer, 5-8 minutes.

Add the flour and mix until just incorporated. Stir in the chocolate chunks. The dough will look somewhat crumbly but should still hold together.

Divide the dough into two portions, shaping each into a log about 2 inches in diameter. Wrap each tightly in plastic wrap and chill in the fridge for at least 3 hours (for even deeper flavor, chill 8+ hours, or overnight).

When you’re ready to bake, preheat your oven to 350° and line two baking sheets with parchment paper. Remove the logs from the fridge and give them about 10 minutes to soften slightly. Brush each with the beaten egg and roll in the turbinado sugar. Carefully cut into half-inch slices (I found that using a finely serrated tomato knife worked best for this). If the cookies crumble a bit as you cut, don’t worry – just smoosh them back together.

Place on prepared baking sheets, about an inch apart. These don’t really spread so you can fit about 16 to a sheet. Sprinkle each cookie with a few flakes of sea salt (my favorites were the ones the had a little extra salt).

Bake in single batches for 12-14 mins, until the bottoms and edges of the cookies just begin to turn golden brown. Let cool for a minute or two on the pan before moving to racks to cool completely.

Store in an airtight container for up to a week.