01 - Preheat oven to 320°F. Line base of 9-inch springform pan with parchment paper.
02 - Combine crushed biscuits, brown sugar, and melted butter in bowl. Press mixture firmly into pan base. Chill while preparing filling.
03 - Beat cream cheese and granulated sugar in large mixing bowl until smooth and creamy.
04 - Add heavy cream, then beat in eggs one at a time until incorporated.
05 - Mix in cornstarch, Irish cream syrup, vanilla extract, and salt until just combined. Avoid overmixing.
06 - Pour filling over prepared crust and smooth top. Bake 55-60 minutes until center is set but slightly wobbly.
07 - Turn off oven, crack door open, and let cheesecake cool inside for 1 hour.
08 - Refrigerate cheesecake at least 3 hours or overnight before serving.
09 - Whip cream with powdered sugar and Irish cream syrup until soft peaks form. Spread or pipe over chilled cheesecake before serving.