1. **Preheat & Prep:** Preheat your oven to 350°F (175°C). Line a 9×13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.

2. **Make the Crust:** In a medium bowl, whisk together the 1 ½ cups flour and ½ cup sugar. Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs. Press this mixture firmly into the bottom of the prepared pan.

3. **Par-Bake Crust:** Bake the crust for 10–12 minutes until slightly puffed and set. Remove and set aside (leave oven on).

4. **Make Cheesecake Filling:** In a large bowl, beat the softened cream cheese and ½ cup sugar until smooth and creamy. Add the eggs and vanilla extract. Beat just until combined. Pour the filling over the warm crust and spread evenly.

5. **Prep Apples:** In a small bowl, toss the diced apples with the sugar, cinnamon, and nutmeg until coated. Sprinkle the spiced apples evenly over the cheesecake layer.

6. **Make Streusel:** In a medium bowl, combine the brown sugar, flour, and oats. Cut in the cold butter until the mixture is crumbly and holds together when squeezed. Sprinkle the streusel over the apples.

7. **Bake:** Bake for 30–35 minutes, or until the filling is set (it may jiggle slightly in the center) and the topping is golden brown.

8. **Cool & Chill:** Remove from oven and let cool completely at room temperature (about 1 hour). Then, refrigerate for at least 2 hours to firm up the cheesecake layer.

9. **Serve:** Lift the bars out of the pan using the parchment paper. Cut into squares. Drizzle generously with salted caramel sauce just before serving.