Prepare the Dough:
Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
In a bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
In a separate large bowl, cream the softened butter and granulated sugar together until light and fluffy (about 3-4 minutes).
Add the egg, vanilla extract, red food coloring, and buttermilk to the butter mixture and mix well.
Combine Wet and Dry Ingredients:
Gradually add the dry mixture to the wet ingredients, mixing until the dough forms. If the dough feels too soft, chill it in the fridge for 30 minutes.
Roll and Cut:
Roll the dough out on a floured surface to about ¼-inch thickness. Use a heart-shaped cookie cutter to cut out cookies.
Place the cookies on the prepared baking sheet and bake for 8-10 minutes, or until the edges are firm.
Make the Icing:
In a small bowl, combine the powdered sugar, vanilla extract, and enough milk to create a smooth icing.
Decorate:
Once the cookies have cooled, drizzle or pipe the icing onto the cookies. Add colorful sprinkles for extra flair.