01 - Preheat the oven to 350°F. Line a 9x9-inch baking pan with parchment paper, allowing overhang on sides for easy removal of bars later.
02 - In a large bowl, combine flour, sugar, and salt. Add cold cubed butter and cut into the dry ingredients using a pastry cutter or your fingertips until mixture becomes crumbly. Stir in vanilla extract.
03 - Reserve approximately 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 layer.
04 - Place the pan in oven and bake the crust for 12 minutes until set. Remove from oven and set aside while preparing the filling.
05 - While crust bakes, combine sliced apples with lemon juice in a bowl. Add sugar, flour, and cinnamon, tossing thoroughly to coat all apple slices evenly.
06 - Spread the apple mixture evenly over the partially baked crust. Drizzle caramel sauce generously over the apple layer.
07 - Sprinkle the reserved crumb mixture evenly across the top, covering the caramel and apples completely.
08 - Return to oven and bake for 28 to 32 minutes until the topping turns light golden brown and apples feel tender when pierced.
09 - Allow bars to cool completely in the pan. Using parchment overhang, lift out the entire batch and cut into 16 even bars.