01 - Preheat the oven to 320°F. Grease and line a 9-inch springform pan.
02 - Crush the biscuits into fine crumbs and mix thoroughly with melted butter. Press firmly into the bottom of the prepared pan, then chill while preparing the filling.
03 - In a large bowl, beat the softened cream cheese with granulated sugar until smooth and creamy.
04 - Add the eggs one at a time, beating well after each addition until fully incorporated.
05 - Mix in cornstarch, then add heavy cream, Irish cream syrup, and vanilla extract. Continue beating until the mixture is completely smooth.
06 - Pour the filling over the chilled crust. Tap the pan gently to release air bubbles, then bake for 55 to 65 minutes until edges are set and center still jiggles slightly.
07 - Turn off the oven, crack the door open, and allow the cheesecake to cool gradually for 1 hour.
08 - Remove from oven and refrigerate for at least 4 hours, preferably overnight, to set completely.
09 - Whip heavy cream with powdered sugar until soft peaks form. Spread or pipe over the chilled cheesecake and garnish with grated chocolate or cocoa powder.
10 - Slice with a clean, hot knife and serve chilled.