In a food processor, combine about 2 cups of vanilla wafers and ½ cup of pistachios. Pulse until sandy crumbs. Gradually add 6 tablespoons melted unsalted butter, mixing fully. Press into a 9-inch pie plate and chill for 30 minutes.

Whip 1 cup of heavy cream in a mixing bowl to stiff peaks; set aside. In another bowl, mix 8 ounces mascarpone, 1 cup powdered sugar, and orange zest until fluffy. Gently fold in 1 cup ricotta until creamy.

Fold half of the whipped cream into the ricotta and mascarpone mixture to lighten it. Gently fold in the remaining whipped cream until no streaks remain.

Spread the filling evenly into the chilled crust. Cover with plastic wrap and refrigerate for at least 4 hours or overnight to set.

Before serving, garnish with mini chocolate chips and a dusting of powdered sugar. Slice and serve chilled.