Preheat the oven to 325ºF. Line a muffin tin with 12 paper liners.
Prepare the crust. In a small bowl, mix the graham cracker crumbs, sugar, cinnamon, and salt. Then, mix in the melted butter using a fork until well combined. Divide this mixture between prepared muffin liners. Press it down to make a crust. Bake in the preheated oven for 5 minutes. Then, remove from the oven and set aside.
Prepare the streusel topping. In another bowl, mix together flour, oats, light brown sugar, cinnamon, nutmeg, and salt. Then, add the cold cubed butter. Combine with your fingers or using a fork until the mixture resembles coarse sand. Place in the refrigerator until ready to use.
Prepare the apple filling. In a bowl, combine the chopped apples, lemon juice, and cinnamon. Set aside.
Prepare the cream cheese filling. In a mixing bowl, combine the cream cheese, sugar, and vanilla extract, using an electric mixer, until smooth. Beat in the eggs, one at a time, beating on low after each addition. Then, whisk in the sour cream using a hand whisk until just combined.
Pour the cream cheese filling over the prepared crust. Divide the apples evenly over the cheesecake layer. Sprinkle the streusel topping on top.
Bake in the preheated oven for 23-26 minutes or until set. Then, remove from the oven and let cool to room temperature. Refrigerate for at least 3 hours before serving. Enjoy with a drizzle of caramel sauce or with whipping cream.