Ingredients
For the Shortbread Crust and Crumb Topping:
2 ½ cups (300g) all-purpose flour
¾ cup (150g) granulated sugar
½ teaspoon salt
1 cup (226g) unsalted butter, very cold and cut into ½-inch cubes
1 teaspoon pure vanilla extract (optional, but highly recommended)
For the Salted Caramel Filling:
1 cup (226g) unsalted butter
1 cup (200g) packed light brown sugar
½ cup (120ml) heavy cream
1 (14-ounce) can (397g) sweetened condensed milk
1 teaspoon pure vanilla extract
½ teaspoon salt (fine sea salt or table salt)
1-2 teaspoons flaky sea salt, for sprinkling (like Maldon or fleur de sel)
Instructions
Prepare for Baking: Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides to easily lift the bars out later. Lightly grease the parchment paper.
Make the Shortbread Crust: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, and ½ teaspoon of salt. If using, add the vanilla extract now.
Cut in the Butter: Add the very cold, cubed butter to the flour mixture. Using a pastry blender, your fingertips, or a food processor, cut the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining. Be careful not to overwork the dough; the colder the butter, the flakier the crust.
Form the Bottom Layer: Press about two-thirds of the crumb mixture evenly into the bottom of the prepared 9×13-inch baking pan. Reserve the remaining one-third of the crumb mixture for the topping.
Blind Bake the Crust: Bake the pressed crust for 15-18 minutes, or until it’s lightly golden brown around the edges. Remove from the oven and set aside while you prepare the caramel. Keep the oven on.
Prepare the Caramel Filling: In a medium-sized heavy-bottomed saucepan, combine the 1 cup of butter, brown sugar, heavy cream, and sweetened condensed milk. Place the saucepan over medium heat.
Cook the Caramel: Bring the mixture to a gentle boil, stirring constantly with a whisk or rubber spatula to prevent scorching. Once boiling, reduce the heat to medium-low and continue to boil gently, stirring frequently, for 5-7 minutes, or until the caramel has thickened considerably and turned a rich amber color. It should coat the back of a spoon. Be patient and don’t rush this step; proper thickening is key to a stable caramel.
Finish the Caramel: Remove the saucepan from the heat. Stir in the 1 teaspoon of vanilla extract and ½ teaspoon of salt. Be cautious, as the caramel will be very hot.
Assemble the Bars: Pour the hot caramel evenly over the pre-baked shortbread crust in the pan.
Add the Topping: Crumble the reserved one-third of the shortbread mixture evenly over the top of the caramel layer.
Final Bake: Return the pan to the oven and bake for an additional 25-30 minutes, or until the crumb topping is golden brown and the caramel is bubbly around the edges and appears set (it will still be soft in the center).
Cool Completely: This step is CRUCIAL for clean cuts! Remove the pan from the oven and place it on a wire rack to cool completely at room temperature. This will take at least 2-3 hours, or even longer. For best results, you can chill the bars in the refrigerator for at least 1 hour once they’ve cooled down to room temperature.
Sprinkle and Cut: Once completely cooled and set, use the parchment paper overhang to lift the entire slab of bars out of the pan. Sprinkle generously with flaky sea salt over the top. Using a sharp knife, cut the slab into 16-24 squares or rectangles, depending on your desired size. For cleaner cuts, you can warm your knife under hot water and wipe it dry between slices.
Serve and Enjoy: Serve at room temperature or slightly warmed. Store any leftover bars in an airtight container.