Preheat oven to 350°F (180°C). Line a 13x9-inch baking pan with foil, letting excess extend over sides of pan. Spray foil with baking spray with flour.

For crust: In the bowl of a stand mixer fitted with the paddle attachment, beat butter and brown sugar at medium speed until creamy, 2 to 3 minutes, stopping to scrape sides of bowl. With mixer on low speed, gradually add flour and salt, beating until just combined. Press mixture into bottom of prepared pan.

Bake until golden brown, about 20 minutes. Let cool completely. Leave oven on.

For filling: In a large bowl, stir together apples, ½ cup (100 gram) granulated sugar, 1 teaspoon (2 grams) cinnamon, and nutmeg. Let stand until apples have released most of their juices, 45 minutes to 1 hour. Drain apples, discarding liquid.

In the bowl of a stand mixer fitted with the paddle attachment, beat cream cheese, eggs, vanilla, and remaining ¾ cup (150 grams)granulated sugar at medium-high speed until smooth, 2 to 3 minutes. Pour onto cooled crust. Gently spread apple mixture on top.

In a medium bowl, whisk together flour, brown sugar, oats, salt, and remaining ½ teaspoon (1 gram) cinnamon. Using a pastry blender or fork, cut in butter until mixture resembles coarse crumbs. Stir in pecans; sprinkle onto apples.

Bake until center is set and an instant-read thermometer inserted in center registers 160°F (71°C), about 45 minutes. Let cool completely in pan on a wire rack. Refrigerate, uncovered, until cold, at least 8 hours or up to overnight.

Using excess foil as handles, remove from pan, and cut into bars. Serve with Salted Caramel Sauce.