Apple Crisp Cheesecake

Preheat oven to 325° and grease an 8" or 9" springform pan with cooking spray.  Make crust: In a large bowl, mix together graham cracker crumbs, melted butter, cinnamon, sugar, and salt. Press into bottom of prepared pan and up the sides. In a large bowl using a hand mixer (or in the bowl of a stand mixer), beat cream cheese, caramel, and sugar together until completely smooth. Add eggs, one at a time, then stir in sour cream and vanilla. Add flour, salt, and cinnamon and beat until just combined. Pour mixture over crust. In a medium bowl, whisk together brown sugar, flour, oats, cinnamon, and salt, then cut in butter with a fork or pastry cutter. Scatter apples in an even layer over top of cheesecake, then top with an even layer of the oat topping. Wrap bottom of pan in aluminum foil and place in a large roasting pan. Pour in enough boiling water to come up halfway in the baking pan. Bake until center of cheesecake only slightly jiggles, about 1 hour 30 minutes.  Turn off oven, prop open oven door, and let cheesecake cool in oven, 1 hour. Remove foil and refrigerate cheesecake for at least 4 hours and up to overnight. When ready to serve, drizzle with caramel and serve slices topped with whipped topping, if desired.