1. Preheat the oven to 350°F (175°C). Line a 9×9-inch baking pan with parchment paper and lightly grease it.

2. In a large bowl, combine the flour, granulated sugar, and salt.

3. Add the cold cubed butter and vanilla extract, then mix using a pastry cutter or fork until crumbly.

4. Reserve 1 cup of the crumb mixture for the topping.

5. Press the remaining crumb mixture firmly into the prepared baking pan.

6. Bake the crust for 15–18 minutes until lightly golden around the edges.

7. While the crust bakes, prepare the caramel filling by combining butter, brown sugar, corn syrup, sweetened condensed milk, and salt in a saucepan over medium heat.

8. Stir continuously for 6–8 minutes until the caramel thickens and becomes smooth.

9. Remove the caramel from the heat and stir in the vanilla extract.

10. Pour the caramel evenly over the baked crust.

11. Sprinkle the reserved crumb topping evenly over the caramel layer.

12. Add chopped nuts or flaky sea salt if desired.

13. Bake for 20–25 minutes until the topping is lightly golden and the caramel bubbles gently.

14. Allow the bars to cool completely at room temperature.

15. Refrigerate the bars for 1 hour before slicing for cleaner cuts.

16. Slice into squares and drizzle with extra caramel sauce before serving if desired.