Finely crush about 16 chocolate crème sandwich cookies in a food processor until they resemble sand. Melt 4 tablespoons of unsalted butter and combine it with the crushed cookies in a large mixing bowl, ensuring all crumbs are coated. Divide this mixture evenly among small glasses, pressing firmly into the bottom to create a solid crust. Refrigerate for at least 30 minutes to set and firm up.

In a mixing bowl, beat 1 cup of mascarpone cheese, ½ cup of chocolate hazelnut spread, ¼ cup of powdered sugar, and 1 teaspoon of vanilla extract using a handheld mixer until the mixture is smooth and creamy, about 2-3 minutes. In a separate chilled bowl, whip 1 cup of heavy cream until soft peaks form. Gently fold one-third of the whipped cream into the mascarpone mixture, followed by the remaining cream until fully incorporated and light.

Once the cookie crusts have set, scoop the mascarpone cream over the chilled crust in each glass, filling them evenly. Use a spatula to smooth the tops for a beautiful finish. Cover the glasses with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, allowing the flavors to meld and the dessert to firm up nicely.

Before serving, remove the cups from the refrigerator and top generously with whipped cream. Garnish with chocolate flakes, chopped nuts, or fresh mint leaves as desired.