Prep the pan: Line the bottom of a 9-inch (23 cm) springform pan with parchment. Lightly grease the sides if you like for easier release.
Make the crust: In a bowl, mix graham crumbs, sugar, and salt.
Stir in melted butter until the mixture feels like damp sand and clumps when pressed.
Press and chill: Firmly press the crust into the bottom of the pan and slightly up the sides. Use the bottom of a measuring cup to compact it. Chill for 15–20 minutes.
Cook the raspberry sauce: In a small saucepan, add 1 1/2 cups raspberries, sugar, and lemon juice.
Cook over medium heat, stirring, until the berries break down and release juices, about 5 minutes.
Thicken the sauce: Stir in the cornstarch slurry and cook 1–2 minutes until glossy and thick. Remove from heat, stir in vanilla if using, and let cool to room temperature. Reserve the remaining 1/2 cup raspberries for folding or garnish.
Beat the cream cheese: In a large bowl, beat cream cheese until very smooth, about 2 minutes.
Scrape the bowl. Add powdered sugar, vanilla, lemon zest, and lemon juice. Beat until creamy and no lumps remain.
Whip the cream: In a separate cold bowl, whip the heavy cream to stiff peaks.
Do not overbeat; it should be firm but still silky.
Combine gently: Fold one-third of the whipped cream into the cream cheese to lighten it. Fold in the remaining whipped cream until no streaks remain.
Flavor the filling: Fold in 1/3 to 1/2 cup of the cooled raspberry sauce to create a light ripple. You can keep it marbled or fully mix for a pink filling.
Avoid overmixing.
Assemble: Spoon the filling over the chilled crust. Smooth the top with an offset spatula.
Top with sauce: Spread the remaining raspberry sauce over the top in a thin, even layer. Add a handful of the reserved raspberries on top if you like.
Chill to set: Cover and refrigerate at least 6 hours, preferably overnight, until the cheesecake is firm and sliceable.
Release and serve: Run a thin knife around the edge before unclipping the springform.
Garnish with fresh raspberries, lemon slices, or mint. Slice with a hot, dry knife for clean cuts.