Prepare your pan: Line the bottom of a 9-inch (23 cm) springform pan with parchment. Lightly grease the sides to help with clean release.
Make the crust: In a bowl, combine cookie crumbs, melted butter, sugar, and a pinch of salt. Stir until the texture feels like damp sand.
Press firmly into the pan base with the bottom of a glass. Chill while you make the filling.
Whip the cream: Beat the cold heavy cream to soft peaks. Don’t overwhip.
Set aside in the fridge.
Blend the mango: Puree the mango until completely smooth. Taste and add lime juice to brighten. Aim for a vibrant, sweet-tangy flavor.
Soften the cream cheese: In a large bowl, beat the cream cheese, powdered sugar, vanilla, and a pinch of salt until smooth and fluffy.
No lumps.
Bloom and dissolve the setting agent: For gelatin, sprinkle it over 3 tbsp cold water and let sit 5 minutes. Gently warm until fully melted (microwave in short bursts or use a small pan). For agar, sprinkle into 3 tbsp water and simmer for 1–2 minutes, whisking, until fully dissolved.
Stabilize with mango: Stir 2–3 tablespoons of the mango puree into the warm gelatin or agar mixture to temper it.
Then whisk this mixture into the remaining mango puree until well combined.
Combine filling: Beat the mango puree into the cream cheese mixture until smooth. Gently fold in the whipped cream with a spatula until just combined. The filling should be light and uniform.
Fill the pan: Pour the filling over the chilled crust.
Smooth the top with an offset spatula. Tap the pan lightly to release air bubbles. Chill for at least 3–4 hours, or until mostly set.
Add the topping: Bloom/dissolve the topping gelatin or agar with the water as above.
Mix into the mango puree with lime juice and sugar if using. Let it cool to just warm, then pour gently over the set cheesecake layer. Tilt to spread evenly.
Chill again: Refrigerate at least 2 more hours, or until the topping is fully set.
Overnight is best for clean slices and fuller flavor.
Unmold and garnish: Run a thin knife around the edge, release the springform, and transfer to a serving plate. Garnish with mango slices, lime zest, or mint. Slice with a hot, dry knife for neat edges.