1. In a medium-sized mixing bowl, whisk together the flour, cocoa powder, baking soda, and salt.
2. In a second bowl, beat together the butter, brown sugar and granulated sugar until creamy. Add the egg, vanilla and milk, and stir well until smooth. Add the dry ingredients, and stir until the mixture comes together in a soft thick dough.
3. Using a tablespoon measure, scoop out dough and shape into 1-inch balls. Roll in granulated sugar to coat and place on a small baking sheet, leaving an inch of space between the balls.
4. Using your thumb or the end of a spatula, make an indentation in the middle of each cookie. Chill for 1 hour, or until firm.
5. Preheat the oven to 350F. Line a large baking sheet lined with parchment paper.
6. Arrange the chilled cookies on the prepared baking sheet, spacing them about 2" apart. Bake for 12-14 minutes, or until the cookies are puffed and edges are set. If the indents have puffed up slightly, use the end of a spatula to push them down again.
7. Allow the cookies to cool on the plan for 5 minutes, then transfer to a wire rack to cool completely before filling.

Fill the Cookies:

1. While the cookies are cooling, prepare the ganache. In a small bowl, microwave the chocolate and cream together on High in 30-second intervals, until melted and smooth. Set aside to cool for 15 minutes.
2. Once the cookies are cooled, spoon some ganache into each indentation - you want it to be mostly full, but not overflowing. Place a single cherry on top of the ganache.
3. Let the cookies sit for another 30 minutes before serving to allow the ganache to set up.

Recipe adapted from Sally's Baking Addiction