01 - Preheat oven to 320°F. Lightly grease a 9-inch springform pan and line the bottom with parchment paper.
02 - Crush biscuits into fine crumbs using a food processor or rolling pin. Combine with melted butter in a bowl until mixture resembles wet sand. Press firmly and evenly into the bottom of the prepared pan. Refrigerate while preparing filling.
03 - In a large mixing bowl, beat softened cream cheese and granulated sugar with an electric mixer on medium speed until completely smooth and creamy, approximately 2-3 minutes. Scrape down bowl sides as needed.
04 - Add eggs one at a time, beating thoroughly after each addition until fully incorporated. This step is crucial for achieving smooth texture.
05 - Sprinkle cornstarch over the mixture and beat on low speed until just combined.
06 - Pour in heavy cream, alcohol-free Irish cream syrup, and vanilla extract. Beat on medium-low speed until mixture is completely smooth and uniform, approximately 1 minute.
07 - Pour filling over the chilled crust. Gently tap the pan on the counter several times to release trapped air bubbles.
08 - Bake for 55-65 minutes, or until edges are set and firm while the center still has a slight jiggle when gently shaken. The center will continue cooking as it cools.
09 - Turn off oven and crack the door open slightly. Leave cheesecake inside for 1 hour to cool gradually and prevent cracking.
10 - Remove from oven and refrigerate for at least 4 hours, preferably overnight, until fully set.
11 - Whip cold heavy cream with powdered sugar until soft peaks form. Spread or pipe decoratively over the chilled cheesecake. Garnish with grated chocolate or dust with cocoa powder before serving.