Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the egg, vanilla extract, and food coloring to the butter-sugar mixture and mix until combined.
In a separate bowl, whisk together the all-purpose flour, cocoa powder, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, alternating with buttermilk, and mix until just combined.
Scoop out tablespoon-sized portions of the dough and roll them into balls.
Place the dough balls on a prepared baking sheet, leaving enough space between each cookie.
Use your thumb or the back of a spoon to create an indentation in the center of each cookie before baking.
Bake for 10-12 minutes, or until the edges are set but the centers still look slightly soft.
Remove from the oven and let cool completely before frosting the centers with cream cheese frosting.