How to make a no-bake chocolate mousse cake

• Crush the Oreo cookies into fine crumbs - I process them in a food processor - and add the melted butter - mix.
  20 pieces Oreo cookies, 60 g butter
  
• Line the bottom of the mold with baking paper, lightly grease the sides with butter.
• Add the crushed cookies.
• Press the cookies onto the sides of the mold - to a height of about 3 cm, and use the rest to line the bottom.
  
• Place the mold in the refrigerator.
• Break the chocolates into smaller pieces and melt them - I melted them in separate bowls. I heated each in the microwave for about 2 minutes (in 30-second intervals). Mix the chocolates thoroughly and set aside to cool slightly.
  200 g milk chocolate, 200 g dark chocolate
  
• Cover the gelatin with a little water - just enough to cover it - and set aside to swell.
  1 tablespoon gelatin
  
• Whip the cold heavy cream until it is thick.
  500 ml heavy cream
• Add a spoonful of whipped cream to the chocolates and mix them.
  
• Transfer the chocolates to a bowl with the whipped cream and mix thoroughly.
  
• Briefly heat the gelatin, and when it becomes liquid, add a spoonful of chocolate mousse to it and mix.
  
• Pour the gelatin into the rest of the mousse and mix thoroughly.
• Transfer the mousse to the mold with the chilled Oreo cookie crust.
  
• Place the tart in the refrigerator to chill.
• Whip the cold heavy cream with powdered sugar until it is thick.
  250 ml heavy cream, 2-3 tablespoons powdered sugar
• Spread the whipped cream on top of the cake.
• You can additionally sprinkle the top with chopped cookies or grated chocolate.