First, preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper to prevent sticking and make cleanup super easy.
In a mixing bowl, beat together the softened butter, brown sugar, and granulated sugar until the mixture is light and wonderfully fluffy.
Next, stir in the egg yolk, vanilla extract, and that vibrant red food coloring until everything is beautifully combined and evenly colored.
Gently add the flour, cocoa powder, baking powder, and salt to the wet ingredients. Mix just until the dry ingredients disappear into the dough – be careful not to overmix!
Scoop out the cookie dough using a tablespoon, then roll each portion into a smooth ball between your palms. Give each ball a lovely sparkle by rolling it in the red sanding sugar.
Place your glittering cookie dough balls onto the prepared baking sheet, leaving a little space between each one, and bake for about 10 minutes. They should look set but still feel soft.
As soon as the cookies come out of the oven, immediately press a Hershey's Kiss right into the center of each warm cookie. The heat will slightly melt the chocolate, creating a perfect blossom effect.
Let these delightful cookies cool on the baking sheet for 10 minutes before carefully transferring them to a wire rack to cool completely. Get ready to share the love!