Prepare Pan and Blind-Bake Shortbread Crust: Preheat your oven to 350°F (175°C). Line a 9x13-inch metal baking pan with parchment paper, leaving an overhang on the sides for easy lifting later. In a food processor or medium bowl using a pastry cutter, pulse or cut together flour, brown sugar, cold cubed butter, and salt until crumbly. Press the mixture firmly into an even, compact layer across the bottom of the prepared pan. Bake for 14 to 15 minutes until lightly golden around the edges; set aside to cool slightly.

Beat the Silky Cheesecake Layer: In a large bowl with an electric hand mixer, beat the softened cream cheese and granulated sugar on medium speed for 2 minutes until creamy and completely smooth. Beat in the eggs one at a time, followed by the vanilla extract and sour cream, beating on low speed just until combined (do not whip too much air into the batter). Pour the cheesecake batter evenly over the warm pre-baked shortbread crust.

Toss Spiced Apples: In a medium bowl, toss the finely diced Honeycrisp apples with 2 tablespoons brown sugar, ground cinnamon, and nutmeg until every apple piece is coated in fragrant spice. Scatter the spiced apples evenly over the raw cheesecake layer.

Make Crunchy Oat Streusel Topping: In another bowl, combine rolled oats, dark brown sugar, flour, and cold cubed butter. Use your fingertips or a fork to rub the butter into the dry ingredients until coarse pea-sized crumbly clusters form. Scatter the streusel evenly across the apples and cheesecake.

Bake to Golden Perfection: Bake uncovered at 350°F (175°C) for 32 to 36 minutes until the streusel is crisp and deeply golden brown, and the cheesecake center is set with only a very slight gentle jiggle. Remove from the oven and cool completely to room temperature on a wire rack for 1 hour.

Chill, Drizzle Caramel, and Slice: Transfer the pan to the refrigerator and chill for at least 2 hours (this step is essential for clean, sharp, bakery-style cuts). Use the parchment paper handles to lift the entire cheesecake block onto a large cutting board. Using a large chef knife wiped clean between cuts, slice into 16 generous square bars. Drizzle lavishly with warm salted caramel sauce, shower with flaky Maldon sea salt, and serve!