Step 1

Place racks in upper and lower thirds of oven; preheat to 350°. Vigorously whisk 1½ cups (packed; 300 g) light brown sugar and 1 cup (2 sticks) unsalted butter, melted, slightly cooled, in a large bowl until lightened in color and smooth and glossy, about 30 seconds. Whisk in 2 chilled large egg yolks and 1½ tsp. vanilla extract. Adding one at a time and whisking after each addition, sprinkle in ⅔ cup (54 g) unsweetened Dutch-process cocoa powder, 1 tsp. baking soda, and 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt. Whisk in 2 tsp. red gel food coloring, then add 2 cups (250 g) all-purpose flour and fold in with a rubber spatula just until the last streak of flour disappears (be careful not to overmix).

Step 2

Pour ½ cup red sanding sugar (preferably Betty Crocker; about 2 oz.) into a small shallow bowl. Divide dough into 16 equal portions (about 3 Tbsp. or 55 g each) and roll each portion into a ball. Roll each ball in sanding sugar to evenly coat, then divide between 2 parchment-lined baking sheets, spacing 2" apart.

Step 3

Bake cookies, rotating baking sheets top to bottom and front to back after 6 minutes, until puffed up and tops begin to crack, 12–14 minutes. Let cookies cool on baking sheets 5 minutes (they will collapse as they cool), then transfer to wire racks and let cool completely.Do ahead: Cookies can be baked 3 days ahead. Store airtight at room temperature, or freeze in a resealable plastic bag for up to 1 month.