Preheat the oven to 325°F (160°C). Line a muffin tin with paper liners or grease it lightly to prevent sticking.

In a mixing bowl, combine the graham cracker crumbs, sugar, and melted butter until the mixture resembles wet sand. Press about 1 tablespoon of the mixture into the bottom of each muffin cup, creating a firm base.

In a large mixing bowl, beat the softened cream cheese with sugar and vanilla extract until smooth and creamy. Make sure there are no lumps!

Add the eggs, one at a time, mixing well after each addition.

Gently fold in the diced apples, ensuring they are evenly distributed throughout the cheesecake batter.

In a separate bowl, mix together the brown sugar, cinnamon, and oats. Set this aside for later.

Pour the cheesecake batter over the pressed crusts in the muffin tin, filling each cup about three-quarters full. Sprinkle the oat topping generously over the cheesecake batter.

Bake in the preheated oven for about 25 minutes or until the edges are set and the centers are slightly jiggly. Remove from the oven and let them cool completely in the tin.

Once cooled, refrigerate the mini cheesecakes for at least 4 hours or overnight.

Serve chilled, optionally topped with whipped cream or a drizzle of caramel.