Apple pie filling can be done ahead of time. You can make it a couple of days before, or a few hours before you need it, or while cheesecake is baking.
Peel, core and dice the apples.
In a medium pot, over medium heat, melt butter. Add diced apples and stir well.
Add brown sugar, apple pie spice, and vanilla, stir and cover with a lid.
Cook, stirring occasionally, until the apples start to soften. Take off lid.
Cook uncovered, until apples are soft and juices are mostly cooked down. Stir occasionally.
Sprinkle flour over apples and stir well. Cover and cook for a few minutes.
Take off heat and set aside until ready to use. (Or cool and refrigerate in a contained with a lid.)
Preheat the oven to 325 degrees and grease a 9 inch springform pan. You will need a large roasting pan that’s bigger and longer than the springform pan. (I usually use the aluminum foil disposable ones). If you are not sure about your springform holding up in water, you can wrap the outside of the springform pan in heavy duty aluminum foil from bottom up to the sides. (I recommend wrapping the outside of the springform in foil before adding the crust and cheesecake batter.)
Mix the graham cracker crumbs, sugar, melted butter, and apple pie spice. Stir very well, until all incorporated. Press graham cracker mixture into the pan, evenly, all over the bottom and about half way up the side.
Start beating cream cheese and sugar on medium-high speed until smooth, about 2 minutes.
Add vanilla extract and sour cream. Mix until combined.
Add eggs, one at the time, beating after each addition. Scrape sides and bottom of the bowl and beat until all incorporated.
Lower speed to low and add corn starch and cinnamon.
Bring the speed up a little and start to pour in heavy cream. Mix until all combined, scrape the sides and bottom of the bowl and mix again for another minute or so, until smooth.
Pour the cheesecake batter into the prepared pan with crust and make sure it's spread evenly.
Place roasting pan into the oven and place the cheesecake springform pan inside the roasting pan. Carefully add hot water to the roasting pan, about half way up the side of the springform.
Bake for 70-75 minutes. Turn off the oven and open the oven door half way. Let cheesecake rest for about 10 minutes and take it out of the oven (out of the roasting pan and carefully take off the foil).
Let it rest for 20 minutes on the counter and then gently run a greased butter knife between sides of the cheesecakes and the springform to carefully separate it. (You don't actually have to take the cheesecake out of the pan until ready to serve.)
Cool cheesecake for an hour.
While still in the springform, scoop warm (or room temperature) apple pie topping over the cheesecake and gently spread it evenly. Cover and refrigerate for at least 4 hours.
When you're ready to serve the cheesecake, spread toffee crunch pieces all over the top. NOTE: don't add toffee crunch pieces ahead of time because they will soften. Add before serving.