Add the butter and powdered sugar to the bowl of an electric mixer fitted with the paddle attachment and beat until the mixture is nice and smooth. Mix in the vanilla and egg. Add the flour, cocoa powder and salt and mix just until the dough comes together. Press a piece of plastic wrap onto the surface of the dough and refrigerate it for a couple of hours.
While the dough is chilling away, unwrap the candies and place them in two plastic bags, separated by color. Crush the candies to pieces with a rolling pin. Throw the crushed mints into separate bowls and set aside.
Preheat the oven to 375 degrees F.
Roll the dough into balls. Place the balls onto baking sheets lined with parchment paper or baking mats. Flatten them slightly with the bottom of a coffee mug or glass. Bake until just set, 7 to 9 minutes. Let the cookies cool completely.
Meanwhile, melt the almond bark in a double boiler or microwave-safe bowl and stir until smooth. One at a time, dip the cooled cookies halfway into the melted almond bark. Sprinkle the top sides generously with crushed mints, holding the cookies over the bowls to catch the excess. You can mix red and green on the same cookie, or do some with just red and some with just green.
Lay the cookies, sprinkled-side up, on parchment paper or a baking mat and allow them to set completely. Serve with a few whole mints on the side.