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 until fully combined. Gradually add flour until mixture resembles coarse sand.

Press about two-thirds of the crumb mixture firmly into the bottom of your prepared pan.

In a separate bowl, toss sliced apples with ground cinnamon and nutmeg, then layer evenly over the crumble base.

Drizzle salted caramel sauce generously over the apple layer.

Scatter the remaining crumb mixture over the caramel-covered apples.

Bake in the preheated oven for 40 to 45 minutes until topping is golden brown and apple filling is bubbling.

Remove from oven and allow to cool completely in the pan before slicing.

Lift the bars out of the pan using the parchment paper and slice into squares or rectangles.