Preheat the oven to 350°F (177°C).

In a food processor or blender, pulse 22 Oreos (including the cream filling) into a fine crumb. You should have about 2 cups (packed) crumbs, or 250g. Pour crumbs into a large bowl. Add the melted butter and stir to combine. The mixture will be thick and quite wet. Try to smash/break up any large chunks. Pour the mixture into an ungreased 9-inch pie dish. With medium pressure using your hand, pat the crumbs down into the bottom and up the sides to make a compact, thick crust. (See this Oreo crust page for more success tips if needed.) Bake for 10 minutes. Allow to cool completely.

Place chopped chocolate in a medium heatproof bowl. Heat the cream in a small saucepan over medium heat, stirring occasionally. As soon as it begins to simmer, immediately remove from heat and pour over the chocolate. Let sit for 2–3 minutes to soften the chocolate, then pour in the hazelnut liqueur, if using. Stir gently until the ganache is smooth. Set aside at room temperature and allow to slightly cool and thicken.

Using a hand mixer or a stand mixer fitted with a whisk attachment, beat the heavy cream on medium-high speed until stiff peaks form, about 3–4 minutes. Spoon the whipped cream into a bowl and set aside. If using a stand mixer, switch to the paddle attachment. Using the same mixing bowl (no need to rinse it out), beat the cream cheese on medium-high speed until completely smooth and no lumps remain. Scrape down the sides of the bowl with a spatula and beat again as needed. Add the Nutella, confectioners’ sugar, and vanilla extract, and beat until combined. Mixture will be thick and may look separated; that’s ok. Gently fold the whipped cream into the Nutella mixture until smooth and combined.

Spread the filling into the cooled crust; I use a small offset spatula for this.

Spread the ganache on top of the filling. Sprinkle with hazelnuts and flaky sea salt.

Chill the pie in the refrigerator for at least 6 hours and up to 48 hours. If chilling for longer than a day, loosely cover it.

Make the whipped cream (add 2 Tablespoons hazelnut liqueur when you add the sugar, if desired) and pipe around the edges of the pie. I used Ateco 826 piping tip for the pictured pie.

Slice and serve cold. Cover leftover pie and store in the refrigerator for up to 5 days.