Preheat the oven to 325°F (160°C).
Prepare the crust by mixing graham cracker crumbs, sugar, and melted butter in a bowl.
Press the crumb mixture into the bottom of a muffin tin lined with paper liners.
In a separate bowl, beat the softened cream cheese and brown sugar until smooth.
Add eggs one at a time, mixing well after each addition, followed by the vanilla extract.
Fold in the diced apples and cinnamon gently until combined.
Pour the cheesecake mixture over the crust in each muffin cup.
In a separate bowl, combine oats, flour, sugar, cinnamon, and nuts for the topping.
Sprinkle the oatmeal mixture generously over each filled muffin cup.
Bake for 25-30 minutes or until the cheesecakes are set but still slightly jiggly in the center.
Allow to cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Chill in the refrigerator for at least 2 hours before serving.
