Put dark chocolate and heavy cream in a bowl and melt them over a double boiler.
Stir the melted mixture well to make ganache.
Let the ganache cool until it reaches a pipeable consistency.
Prepare the cookie dough and shape it into balls.
Make a dent in the center of each dough ball and fill it with ganache.
Bake the cookies in a 180℃ oven for 12–15 minutes.
Cool completely and wait until the ganache sets.