Prep the pan: Line the bottom of a 9-inch springform pan with parchment. Lightly grease the sides if you like for easy release.

Make the crust: In a bowl, combine chocolate cookie crumbs, melted butter, sugar (if using), and salt. Stir until the mixture looks like damp sand and holds together when pressed.

Press and chill: Firmly press the crumb mixture into the bottom and slightly up the sides of the pan. Use a flat-bottomed glass for an even layer. Chill in the fridge while you make the filling.

Melt the chocolate: Place chopped chocolate in a heatproof bowl. Microwave in 20–30 second bursts, stirring between each, until smooth. Or melt over a double boiler. Let it cool to just warm, not hot.

Beat the cream cheese: In a large bowl, beat the softened cream cheese with sugar until smooth and no lumps remain, about 2 minutes. Scrape the bowl well.

Add cocoa, vanilla, and salt: Mix in the cocoa powder, vanilla, and salt until fully combined. The mixture should look creamy and uniform.

Stream in the chocolate: With the mixer on low, slowly add the melted chocolate and beat until evenly incorporated. Scrape the bowl and beat again briefly.

Whip the cream: In a separate bowl, whip the cold heavy cream to medium-stiff peaks. Don’t overwhip; it should hold its shape but still look smooth.

Fold it together: Gently fold the whipped cream into the chocolate cream cheese mixture in two additions. Use broad, light strokes to keep it airy.

Fill the crust: Spoon the filling into the chilled crust. Smooth the top with an offset spatula. Tap the pan gently on the counter to release any large air bubbles.

Chill to set: Cover and refrigerate for at least 6 hours, preferably overnight, until firm enough to slice cleanly.

Finish and serve: Run a thin knife around the edge and release the springform. Top with whipped cream, chocolate shavings, or berries. Slice with a warm, dry knife for neat edges.