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 unsalted butter, granulated sugar, vanilla extract, and salt. Stir until well-blended. Gradually add flour until crumbly.

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

In a separate bowl, combine sliced apples with ground cinnamon and nutmeg, then layer over the pressed crust.

Drizzle salted caramel sauce over the apple layer.

Sprinkle the remaining crumble mixture evenly over the caramel and apple layers.

Bake for 40-45 minutes or until the crumble topping is golden brown and the apples are tender.

Allow to cool completely in the pan before slicing into bars.