In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set this bowl aside.

In a separate bowl, use a hand or stand mixer to beat the softened butter, brown sugar, and granulated sugar on medium speed for about 3 minutes until creamy.

Add the egg and pure vanilla extract to the butter mixture. Mix on high for about 1 minute, scraping the sides and bottom of the bowl occasionally.

Gradually pour the dry ingredients into the wet mixture. Add the milk and gel red food coloring. Mix on low speed until combined. Adjust food coloring for a vibrant hue if desired.

Cover the bowl with plastic wrap and refrigerate the dough for at least 2 hours or up to 3 days.

Preheat your oven to 350°F (177°C) and line your baking sheets with parchment paper or silicone baking mats.

Scoop about 1.5 tablespoons of dough using a medium cookie scoop, roll into balls, and arrange them on the baking sheet with about 3 inches of space in between.

Bake for 11-13 minutes. The edges should look set; the centers will be soft.

Allow cookies to cool for about 5 minutes on the baking sheets before transferring to a wire rack to cool completely.

In a microwave-safe bowl, melt the white chocolate in 15-second increments, stirring until smooth. If it's too thick, stir in a teaspoon of vegetable oil.

Dip half of each cookie into the melted white chocolate and immediately sprinkle on your favorite sprinkles.

Let the dipped cookies set completely at room temperature or refrigerate for faster setting.