01 - Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper, allowing overhang for easy removal later.
02 - Combine flour, sugar, and salt in a large bowl. Cut in cold butter using a pastry cutter or fingers until mixture becomes crumbly. Stir in vanilla extract.
03 - Reserve 1 1/2 cups of the crumb mixture for the topping. Press remaining dough firmly and evenly into the bottom of the prepared pan to create the crust base.
04 - Bake the crust for 12 minutes until set, then remove from oven.
05 - Toss apple slices with lemon juice in a bowl. Add sugar, flour, and cinnamon, mixing well until apples are evenly coated.
06 - Spread the apple mixture evenly over the hot crust. Drizzle caramel sauce over the apples.
07 - Sprinkle the reserved crumb mixture evenly over the caramel and apple layer.
08 - Bake for 28-32 minutes until topping is light golden brown and apples are tender when pierced.
09 - Cool completely in the pan before lifting out using parchment paper. Cut into 16 bars.