Do I have to chill the dough?
I highly recommend it. Even 30 to 60 minutes makes the dough easier to handle and helps prevent over-spread. If you can do an overnight rest, the flavor gets noticeably deeper and the texture gets chewier.
Why did my cookies spread too much?
Usually one of these: the butter was still too warm when mixed, the dough was not chilled, the baking sheet was hot from a previous batch, or your flour was under-measured. Let the brown butter cool until it is no longer hot and entirely liquid (see note below), and always start on a cool sheet pan.
One more variable: browning butter cooks off water. That can make cookies spread a bit more in some kitchens. If you notice extra spread, chill longer, or stir 1 to 2 tablespoons water or milk into the brown butter after it cools slightly (before adding sugars).
How brown should the butter get?
You want an amber color and a nutty smell, with browned bits on the bottom of the pan. If it smells burnt or looks very dark, it probably is. When in doubt, stop a little earlier next time.
Can I make these without a stand mixer?
Yes. Use a whisk for the butter and sugars, then a sturdy spatula to fold in the dry ingredients. The dough should look thick and scoopable after chilling.
What chocolate works best?
Chopped semisweet or bittersweet chocolate gives you pools and streaks. Chips are totally fine, but chopped bars melt more dramatically.
How do I get more crinkles on top?
Use the 375°F bake, make sure the dough is cold, and pull them when the centers are still a little underdone. The rapid set on the outside plus steam from the cold dough helps create that crinkly top. Results can vary a bit depending on your sheet pans and oven, so treat the timing as a guide and bake to the visual cues.
Convection (fan) oven?
If you bake with convection, reduce the temperature by about 25°F and start checking a minute early.