01 - Preheat your oven to 350°F (175°C). Line a 9x9-inch baking pan with parchment paper, ensuring there's an overhang for easy removal.
02 - In a mixing bowl, combine graham cracker crumbs, granulated sugar, and melted butter. Press this mixture evenly into the bottom of the prepared baking pan. Bake for 8 minutes, then allow it to cool slightly.
03 - Using an electric mixer, beat the softened cream cheese and granulated sugar until smooth. Incorporate the eggs one at a time, mixing thoroughly after each addition. Blend in the vanilla extract. Pour this mixture over the cooled crust and smooth the surface gently.
04 - In a separate bowl, toss the diced apples with light brown sugar, ground cinnamon, and ground nutmeg. Distribute this spiced apple mixture evenly over the cheesecake layer.
05 - Combine all-purpose flour, oats, light brown sugar, ground cinnamon, and salt in a bowl. Using a pastry cutter or your fingertips, cut in the cold, diced butter until the mixture resembles coarse crumbs. Sprinkle this topping evenly over the apple layer.
06 - Bake for 40–45 minutes, or until the center is set and the crisp topping is golden brown.
07 - Allow the dessert to cool completely at room temperature. Refrigerate it for at least 3 hours before lifting it out of the pan using the parchment overhang. Cut into squares for serving.