01 - Preheat your oven to 325°F. Lightly grease a 9-inch springform pan and line the bottom with parchment paper.
02 - In a food processor, pulse the chocolate sandwich cookies until fine crumbs form. Transfer to a bowl and mix with the melted butter until thoroughly combined. Press this mixture firmly into the bottom of the prepared springform pan. Place the pan in the refrigerator to chill while you prepare the filling.
03 - In a large mixing bowl, beat the softened cream cheese and granulated sugar together with an electric mixer until the mixture is smooth and creamy.
04 - Add the eggs one at a time, mixing well after each addition until just combined. Be careful not to overmix.
05 - Blend in the heavy cream, sweetened condensed milk, alcohol-free Irish cream syrup (or the substitute blend), vanilla extract, and cornstarch. Mix on low speed just until the filling is smooth. Avoid overbeating, which can introduce too much air.
06 - Carefully pour the prepared Irish cream filling over the chilled cookie crust in the springform pan. Place the springform pan on a baking sheet to catch any potential drips. Bake for 55 to 65 minutes, or until the edges are set and the center of the cheesecake still has a slight jiggle.
07 - Once baked, turn off the oven and prop the door slightly ajar. Allow the cheesecake to cool gradually inside the oven for 1 hour. This helps prevent cracking.
08 - Remove the cheesecake from the oven and let it cool completely to room temperature on a wire rack. Once cooled, refrigerate the cheesecake for at least 4 hours, or preferably overnight, to allow it to fully set.
09 - For the topping, in a clean bowl, whip the heavy whipping cream with the powdered sugar and vanilla extract until stiff peaks form. Spread or pipe this whipped topping over the thoroughly chilled cheesecake. For an optional decorative touch, garnish with grated chocolate or a dusting of cocoa powder.
10 - When ready to serve, use a clean, sharp knife to slice the cheesecake. For neat slices, wipe the knife clean between each cut.