Preheat your oven to 375°F (190°C) and line a 9x13 inch baking pan with parchment paper.

In a large mixing bowl, combine melted butter, granulated sugar, vanilla extract, and salt. Mix well, then fold in flour until the mixture resembles coarse crumbs.

Press about two-thirds of the crumble mixture evenly into the bottom of the prepared baking pan.

Slice apples and coat with ground cinnamon and nutmeg. Distribute evenly over the crust.

Drizzle salted caramel sauce over the apple layer for even distribution.

Crumble the remaining mixture over the caramel and apple layer.

Bake for 40-45 minutes or until the top is golden brown and the filling is bubbling.

Let the bars cool completely in the pan on a wire rack before slicing.