For years, this was a recipe I didn't let out of my kitchen — I don't know why, but everybody has one or two recipes like that. I finally relented and gave a copy to Rick Bishop, Milk Bar's favorite strawberry farmer, and he told me he hid it under his kitchen sink, where he knew it would be safe.
Reprinted with permission from Momofuku Milk Bar by Christina Tosi, copyright © 2011. Published by Ten Speed Press, a division of Random House, Inc.
Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium-high for 2-3 minutes. Scrape down the sides of the bowl, add the egg, and beat for 7-8 minutes.
Reduce the mixer speed to low and add the flour, corn flour, corn powder, baking powder, baking soda, and salt. Mix just until the dough comes together, no longer than 1 minute. Scrape down the sides of the bowl.
Using a 2-ounce ice cream scoop (or a 1/3-cup measure), portion out the dough onto a parchment-lined sheet pan. Pat the tops of the cookie dough domes flat. Wrap the sheet pan tightly in plastic wrap and refrigerate for at least 1 hour, or up to 1 week. Do not bake your cookies from room temperature because they will not bake properly.
Heat the oven to 350 degrees.
Arrange the chilled dough a minimum of 4 inches apart on parchment- or Silpat-lined sheet pans. Bake for 18 minutes. The cookies will puff, crackle, and spread. After 18 minutes, they should be faintly browned on the edges yet still bright yellow in the center; give them an extra minute if not.
Cool the cookies completely on the sheet pans before transferring to a plate or to an airtight container for storage. At room temperature, the cookies will keep fresh for 5 days; in the freezer, they will keep for 1 month.