Preheat your oven to 350°F. Line a 9-inch springform pan with parchment and lightly grease the sides.
Combine the graham cracker crumbs and melted butter in a bowl. Press into the bottom of the pan to form the crust. Bake for 8 minutes, then set aside to cool.
In a large bowl, beat the cream cheese and granulated sugar until smooth. Add the sour cream and vanilla, mixing until just combined. Add eggs one at a time, mixing on low after each just until blended. Pour over the crust.
Toss chopped apples with brown sugar and cinnamon. Spoon evenly over the cheesecake filling.
For the streusel, mix the flour, oats, brown sugar, and cinnamon. Cut in cold butter until crumbly. Sprinkle generously over the apples.
Bake for 55-65 minutes or until the center is almost set. Let cool completely, then refrigerate at least 4 hours (overnight is best).
Carefully remove from pan and slice to serve. Eat cold or bring to room temp—either way, it’s heavenly.