Preheat a conventional oven to 350°F (175°C) and line a 9x9-inch baking pan with parchment paper.

Combine 2 cups flour and 0.5 cup brown sugar in a bowl; incorporate 0.75 cup softened butter using a pastry cutter until crumbly. Press the mixture firmly into the bottom of the pan.

Par-bake the crust for 15 minutes or until edges reach a light golden hue.

Beat the cream cheese and 0.5 cup granulated sugar at medium speed until homogenous. Incorporate eggs and vanilla extract, mixing until just combined. Spread the batter evenly over the hot crust.

In a small vessel, toss the diced apples with 2 tablespoons sugar, cinnamon, and nutmeg. Distribute the apple mixture uniformly over the cream cheese layer.

Prepare the streusel by mixing 0.5 cup brown sugar, 0.5 cup flour, and oats; cut in 0.25 cup chilled butter cubes until the texture resembles coarse meal. Sprinkle over the apples.

Bake for 30 minutes or until the cheesecake center is stable and the streusel is golden brown.

Cool at room temperature for 1 hour, then refrigerate for at least 2 hours. Drizzle with caramel sauce immediately before slicing into 16 bars.