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, mixing until smooth.

Gradually mix in the all-purpose flour until the texture resembles coarse sand. Press two-thirds of the mixture into the bottom of the pan.

In another bowl, toss sliced apples with ground cinnamon and nutmeg, then layer evenly over the base in the pan.

Drizzle salted caramel sauce over the spiced apple filling, ensuring even coverage.

Crumble the remaining mixture over the apple and caramel layers evenly.

Bake for 40-45 minutes until golden brown and bubbling around the edges.

Let the pan cool completely before slicing for clean bars.