Place the chocolate crème sandwich cookies in a food processor and pulse until finely ground, resembling sand.

Melt the unsalted butter in the microwave for about 30 seconds, then mix it with the crushed cookies until evenly coated.

Spoon the cookie mixture into small glasses, pressing down firmly to create an even crust. Refrigerate the cups for at least 30 minutes until the crust is set.

In a stand mixer, combine the softened mascarpone cheese, chocolate hazelnut spread, powdered sugar, and vanilla extract. Beat until smooth and creamy, about 2–3 minutes.

In a separate bowl, whip the heavy cream until soft peaks form, about 3–4 minutes. Gently fold one-third into the mascarpone mixture, then fold in the remaining whipped cream until fully incorporated.

Spoon the mascarpone mixture over the chilled crusts, smoothing the tops. Cover with plastic wrap and refrigerate for at least 2 hours, preferably overnight.

Before serving, garnish each cup with whipped cream, chocolate curls, crushed nuts, or fresh berries.