Step 1

Place 1 stick unsalted butter in a large microwave-safe bowl. Microwave until almost completely melted in 20-second bursts, 40 seconds to 1 minute total. (Alternatively, heat butter in a small pan over medium heat until melted.) Add 1/2 cup light or dark brown sugar and 1/4 cup granulated sugar, and stir with a flexible spatula until combined and no lumps remain.

Step 2

Add 1 large egg, 1 tablespoon whole or 2% milk, 2 teaspoons vanilla extract, 1 1/2 teaspoons red liquid or gel food coloring, 1 teaspoon distilled white vinegar, and 1/2 teaspoon kosher salt, and stir until combined.

Step 3

Place 1 1/2 cups all-purpose flour, 2 tablespoons unsweetened natural cocoa powder, and 1/2 teaspoon baking soda in a medium bowl and whisk to combine, making sure no lumps of cocoa powder remain. Add to the butter mixture and stir until no dry spots remain.

Step 4

Add 1/2 cup of the white chocolate chips and stir to combine. Refrigerate the dough for at least 30 minutes or up to 1 hour. Meanwhile, arrange 2 racks to divide the oven into thirds and heat the oven to 350°F. Line 2 baking sheets with parchment paper or silicone baking mats.

Step 5

Scoop the dough into 2-tablespoon portions. Place the dough balls at least 1 1/2 inches apart on the baking sheets, 11 per sheet. Press the remaining 1/4 cup white chocolate chips into the tops of the dough balls (3 to 4 each).

Step 6

Bake for 4 minutes. Rotate the baking sheets between racks and from front to back. Bake until the cookies are set around the edges, 4 to 5 minutes more. Let cool for 2 minutes on the baking sheets, then transfer to a wire rack and let cool completely.