Piloncillo Chocolate Chip Cookies

Preparation

1. Step 1

   Grate piloncillo using the large holes of a box grater. The grated piloncillo won’t look or feel like dark brown sugar; it will more closely resemble grated hard cheese and will have crumbly, irregular shapes with some larger split pea-size pieces. (The larger pieces will taste like and have the texture of broken bits of toffee inside the baked cookie.)

2. Step 2

   Whisk grated piloncillo, granulated sugar, butter and kosher salt in a large bowl until evenly mixed. Vigorously whisk in egg and vanilla until mixture lightens in color and becomes almost ribbony but with undissolved pieces of piloncillo, about 1 minute. This step is very important and will give your cookie a shiny top, like a brownie, that will crisp as it bakes.

3. Step 3

   Add flour and baking soda and, using a wooden spoon or rubber spatula, mix until dough comes together and no floury bits remain, about 30 seconds. Stir in chocolate until evenly distributed. Dough will be soft and may be warmer than room temperature. Refrigerate for 30 minutes (or up to 5 days; see Tip) to enhance flavor and allow the dough to firm up. Meanwhile, if baking right away, with racks in the upper and lower thirds, heat oven to 350 degrees.

4. Step 4

   Portion out balls of dough (about 2 generous tablespoons each) and space about 2 inches apart on 2 parchment-lined baking sheets. (You can also form dough into table tennis-size balls with your hands.) Do not flatten; cookies will spread as they bake. Sprinkle each ball with flaky or kosher salt.

5. Step 5

   Bake cookies, 2 sheets at a time, switching the pans halfway through, until edges are brown and firm but centers are still soft, 16 to 18 minutes. Let cool on baking sheets for 10 minutes, then transfer to a wire rack and let cool completely.