Preheat your oven to 350F. This initial step is key to ensuring your bars bake evenly. Line an 8-inch square pan with aluminum foil, leaving an overhang for easy removal later. Spray it with cooking spray or grease it with butter and flour.
In a large bowl, combine 1 cup of all-purpose flour and ¼ cup of light brown sugar. Cut in ½ cup of unsalted butter using two forks, mixing until crumbly, with pea-sized bits forming. This will be your crust.
Turn the mixture into the prepared pan, pressing it down firmly with your fingertips to create an even, flat layer. This will make a solid base for your cheesecake.
Bake the crust for 14 to 15 minutes or until just set. Keep an eye on it; you want it to be firm but not browned. Once baked, remove it from the oven and set aside to cool slightly.
While the crust cools, prepare the cheesecake mixture. In a large bowl (you can use the same one if you wipe it clean), add 8 ounces of softened cream cheese, ½ cup of granulated sugar, 1 large egg, and 1 teaspoon of vanilla extract. Beat with a hand mixer until smooth and creamy, about 2 minutes on high speed.
Next, peel, core, and dice your apples—about 2 cups should do nicely. Place them in a medium bowl and sprinkle with 2 tablespoons of granulated sugar, 1 tablespoon of cinnamon, and ¼ teaspoon of ground nutmeg. Toss everything well to ensure the apples are evenly coated.
In another medium bowl, mix ½ cup of light brown sugar, ½ cup of old-fashioned rolled oats, and ½ cup of all-purpose flour. Cut in the 6 tablespoons of unsalted butter until crumbly bits form. If the mixture is too loose, add a tablespoon or two of flour or oats to reach your desired consistency.
After your crust has cooled slightly, pour the cheesecake mixture over the crust. Smooth it out with a spatula for an even distribution.
Evenly sprinkle the diced apples over the cheesecake layer, followed by the crumble mixture on top. It may look like a lot, but it will sink a bit while baking.
Bake the bars for 45 to 50 minutes, or until the crumble topping is just set and lightly golden. A timer is your friend here to avoid over-baking!
After baking, remove the pan and place it on a wire rack. Allow it to cool for about 30 minutes. This cooling step is vital; it helps the layers set properly.
Once cooled, drizzle ½ cup of salted caramel sauce over the top. Let the bars cool completely in the pan for at least 4 hours, or overnight if possible. Patience is key here!
When ready to serve, lift the bars out using the foil overhang and slice them into squares. Enjoy!
