Grease a 24cm round cake pan by lightly buttering the base and sides with butter (alternatively use margarine). Line the base and sides with baking paper. Refrigerate a large stainless-steel bowl.
To make the biscuit base, place the biscuits in a food processor. Process until the biscuits are finely crushed and resemble breadcrumbs. Add the melted butter and continue to process until well combined. Use a potato masher or the back of a spoon to press the biscuit mixture evenly over the base of the prepared cake pan. Refrigerate for 30 minutes.
To prepare the Crema Chantilly, remove the stainless-steel bowl from the fridge. Pour the thickened cream into the cool bowl. Add the icing sugar and vanilla bean seeds (or vanilla bean paste). Use an electric mixer or hand beater to beat until stiff peaks form. Refrigerate until ready to use.
Place the cream cheese, mascarpone and marsala into a separate large bowl. Beat until well combined.
To make the Tiramisù cheesecake filling, remove the bowl with Crema Chantilly from the fridge. Beat the Crema Chantilly into the cream cheese mixture, one tablespoon at a time until well combined.
Remove the biscuit base from the fridge. Spoon a little over 1/3 of the Tiramisù cheesecake filling over biscuit base. Smooth the surface.
Pour cooled coffee into a shallow bowl. Soak the Savoiardi biscuits in the coffee, one at a time without letting them get completely sodden and giving them a light squeeze as you take them out. The coffee shouldn’t soak all the way through, so there should still be a little portion of biscuit in the middle left untouched. Arrange the coffee soaked Savoiardi biscuits to completely cover the biscuit base.
Spread half of the remaining Tiramisù cheesecake filling over the Savoiardi biscuit layer and smooth the surface. Spoon the remaining filling into a disposable piping bag. Pipe peaks of the filling on the top of the cheesecake to decorate. Use a small strainer to sprinkle unsweetened cocoa powder on top. Refrigerate for a minimum of 4 hours or overnight to set before serving – buon appetito.
Note: If you have any cheesecake left over, store in the fridge for 2-3 days.