For the chocolate cookie cake, crumble the cookies. Heat the margarine and mix with the cookie crumbs. Grease a cake mold or line with plastic wrap.
Press the mixture into the mold as a base and chill. After 30 minutes, spread the jam on top. Refrigerate again. Take 6 tablespoons of the cocoa and put it into a small bowl.
Whip the cream cheese with the sweetener and the cocoa residue. Dissolve the gelatine in the cocoa, warming slightly but not boiling. Whisk the gelatin mixture into the cream cheese mixture. Pour the mixture onto the cold cake base and refrigerate for at least 3 hours.
Sprinkle the chocolate cookie cake with shaved chocolate if desired.