Sugar Cookies

Method

1. mix3 min
   medium-high, butter at 65°F
   butter + 0.67 cup sugar, beaten until visibly paler and increased in volume — the sugar crystals are cutting air pockets into the fat, and that mechanical aeration is the only leavening that matters here. Butter warmer than about 70°F is too slack to hold the pockets and the cookies spread into wafers; butter straight from the fridge won't take them at all.
2. mix1 min
   medium
   + egg + vanilla, until the mixture is uniform and no longer looks broken — a cold egg chills the butter and curdles the cream, which is why it comes to room temperature first
3. fold2 min
   low speed or by hand, just to disappearance
   + flour + baking powder + baking soda + salt, stopping the moment no dry streaks remain. Past that point you are developing gluten in a batter that has no business being elastic, and the cookies turn tough and domed instead of tender.
4. rest30 min
   refrigerated, covered
   dough chilled until firm enough to scoop cleanly. This does two things: the fat re-solidifies so the edges set in the oven before the cookie can spread, and the flour finishes hydrating, which deepens flavor and stops the surface from going sandy.
5. prep5 min
   oven at 375°F
   dough scooped into 10-12 balls of about 1.5 tbsp each, then each rolled in the reserved granulated sugar and set 2 in apart on a lined sheet. The sugar coat dries the surface so it cracks as the center rises — that crackle is the whole visual signature.
6. bake10 min
   375°F, single sheet, center rack
   until the edges are set and just barely gold and the centers still look underdone and puffed. They are — carryover heat in the sheet finishes them. A cookie baked until the middle looks done is a cookie that will be dry at room temperature.
7. rest5 min
   on the hot sheet, then on a rack
   cookies left on the pan to firm up before moving; lifted too early they fold, and the collapse as they cool is what gives the chewy center