Preheat your oven to 350°F (175°C) and grease your 9x13-inch baking dish with butter or non-stick spray.

In a large mixing bowl, combine the all-purpose flour with salt and whisk thoroughly. Set aside.

In another bowl, cream together the softened butter and granulated sugar until light and fluffy, then stir in vanilla extract.

Gradually add the flour mixture to the butter mixture, mixing on low speed until a crumbly dough forms. Reserve a portion for topping.

Press two-thirds of the dough into the bottom of the greased baking dish.

In a separate bowl, toss the sliced apples with granulated sugar, ground cinnamon, ground nutmeg, lemon juice, and cornstarch.

Evenly distribute the apple mixture over the crust.

Crumble the reserved dough over the top of the apple layer.

Bake in the preheated oven for 40-45 minutes until golden brown.

Allow the bars to cool for at least 30 minutes on a wire rack before slicing.

Optional: Drizzle with caramel sauce before serving.