Preheat the oven to 350º F.
In a mixing bowl beat the butter and brown sugar with an electric mixer for 1 minute, or until combined.
Add in the egg and vanilla extract, beat again.
In a separate small bowl, whisk together the flour, cocoa powder, baking soda, and salt.
Gradually add the dry ingredients to wet ingredients, mixing by hand with a spatula.
The batter will be thick.
Drain and finely chop the maraschino cherries.
Be sure to pat the cherries to absorb as much excess liquid as possible.
Add in the chopped cherries and chocolate chips, mixing with a spatula until combined.
Use a cookie scoop to drop dough balls onto a silicone lined baking sheet.
Press additional maraschino cherry pieces and chocolate chips all around the outside of the dough balls.
Bake for 13-15 minutes.
Allow the cookies to cool to the touch on the baking sheet (about 15 minutes) then move them to a cooling rack.