Preheat the oven to 350°F (175°C) and line a large baking sheet with parchment paper.

Cream the butter, brown sugar, and granulated sugar in a stand mixer until smooth and creamy, about 2-3 minutes.

Combine the egg yolk, vanilla extract, and red food coloring gel into the butter mixture and mix until incorporated.

Whisk together the all-purpose flour, cocoa powder, baking powder, and salt in a separate bowl. Gradually add to the wet ingredients, mixing until a soft dough forms.

Scoop out 18 cookie dough balls, roll them in palms, and coat each in red sanding sugar.

Arrange the cookie balls on the prepared baking sheet, leaving space between them. Bake for 10 minutes and press a Hershey's Kiss into the center of each cookie upon removal from the oven.

Cool the cookies on the baking sheet for about 10 minutes before transferring to a cooling rack.