Espresso Chocolate Chunk Shortbread Cookies

Ingredients

for the dough

255g salted butter, cold, cut into small pieces (or unsalted butter plus 3/4 tsp kosher salt, ish)
100g sugar
50g dark brown sugar
1 tsp vanilla extract
295g flour
170g dark chocolate chunks (I usually use scharffen berger bittersweet)
2 tbsp instant espresso powder (note that this is not the same as just espresso grinds) (optional, I guess? but it’s really good)

for rolling

Beat the butter, regular and brown sugars, and vanilla with an electric mixer until light and fluffy.
Add flour, and mix just until combined.
Add chocolate chunks and espresso powder, mix just until incorporated. (It’ll look crumbly. This is fine.)
Split the dough into halves, and shape each half into a log about 2-2.25” in diameter. Wrap each log in plastic wrap and chill until totally firm, about 2 hours (overnight or even freezing is fine).
When you’re ready to bake the cookies, preheat your oven to 350° F and line two baking sheets.
Lightly beat the egg (like, fork in a bowl, be chill). Set up some of the turbinado sugar in another bowl, this’ll get a bit messy.
Working with your logs of dough one at a time: unwrap the dough (leaving the plastic wrap under it like a plate), brush egg all over the log, and sprinkle the crunchy turbinado sugar generously all over the egg-washed log. Rewrap the log briefly and roll it around, basically just to press the sugar in a bit and encourage more of it to really stick.
Using a sharp serrated knife, cut logs into 1/2-inch thick rounds.
Arrange cookie slices on the prepared baking sheets 1” apart (they don’t spread much) and sprinkle each with a few flakes of salt.
Bake for 12 to 15 minutes, or until the edges are just beginning to get golden brown.

Yeah these are basically the Alison Roman cookies, except I added espresso powder and always use dark brown sugar instead of light.
I love storing these in my freezer and just eating them frozen.
These are basically the perfect cookie.