Preheat oven to 325°F (160°C). Grease a springform pan or line with parchment.
Mix graham cracker crumbs, melted butter, and 1 tbsp sugar. Press into pan to form crust. Bake for 8-10 minutes and let cool.
In a large bowl, beat cream cheese until smooth. Add sugar and mix well.
Blend in eggs one at a time. Add sour cream, heavy cream, and vanilla extract.
Stir in 1 cup mango purée and cornstarch until combined.
Pour mixture over crust. Tap pan gently to remove air bubbles.
Bake for 50–55 minutes or until center is just set. Cool to room temperature.
Chill in refrigerator for at least 4 hours or overnight.
Top with remaining mango purée and fresh mango slices before serving.