Prepare the Cookie Crumble

1. Crush the Cookies: Start by placing the chocolate sandwich cookies into a ziplock bag. Use a rolling pin or your hands to crush them into small pieces. You can make them as chunky or fine as you like, but keeping some larger pieces will add a nice crunch to the mousse.
2. Set Aside: Once the cookies are crushed, set them aside. You’ll be layering them into the mousse later.

Make the Mousse

1. Whip the Cream: In a large mixing bowl, pour in the heavy cream. Using an electric mixer or a whisk, whip the cream until soft peaks form. This should take about 2-3 minutes. Be careful not to overwhip, as it can turn into butter.
2. Add Mascarpone and Powdered Sugar: In another bowl, combine the mascarpone cheese (or cream cheese) with the powdered sugar and vanilla extract. Mix until smooth and well combined.
3. Fold the Whipped Cream into the Mascarpone Mixture: Gently fold the whipped cream into the mascarpone mixture. Use a spatula to carefully combine, ensuring the mousse stays light and fluffy.
4. Add the Cookie Crumble: Gently fold in the crushed cookies, reserving a few pieces for topping. This will give the mousse that perfect cookies-and-cream taste and texture.

Assemble the Mousse

1. Layer the Mousse: Spoon the mousse into serving glasses or bowls. You can create multiple layers by adding a spoonful of mousse, then a sprinkle of cookie crumble, and repeating until the glasses are full.
2. Chill: Cover the mousse and place it in the refrigerator for at least 4 hours. This allows the flavors to meld and the mousse to set to its creamy perfection.
3. Serve: Once chilled, top with the reserved cookie crumble and any other toppings you like, such as a dollop of whipped cream or chocolate shavings.