Preheat oven to 375°F (190°C) and line baking sheets with parchment paper.

In a medium bowl, whisk together flour, cocoa powder, baking soda, and salt.

In a large bowl, cream together butter, peanut butter, 1/2 cup granulated sugar, and brown sugar until light and fluffy.

Beat in the egg, milk, vanilla extract, and red food coloring until the color is uniform.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Shape dough into 1-inch balls and roll each ball in the extra granulated sugar to coat.

Place balls 2 inches apart on prepared baking sheets.

Bake for 8 to 10 minutes or until the edges are set.

Immediately press a chocolate kiss into the center of each cookie allowing the edges to crack slightly.

Transfer to a wire rack to cool completely so the chocolate resets.