The bars are delicious and addictive. I'm glad I added the salt; it adds additional complexity to the dessert.
Caramel crumb bars
1 cup (224g/2 sticks) unsalted butter, softened
½ cup (100g) granulated sugar
1 teaspoon vanilla extract
1/8 teaspoon salt
2 ½ cups (350g) all purpose flour, divided use
¼ cup (56g) unsalted butter, softened
¼ cup packed brown sugar
1 tablespoon light corn syrup
1 395g (14oz) can sweetened condensed milk
Preheat the oven to 180°C/350°F. Lightly butter a 32x22cm (13x9in) baking pan, line with foil, butter and flour the paper and the sides of the baking pan*.
Start by making the crust: in a mixer fitted with the paddle attachment, beat together the butter, sugar, vanilla, and salt until creamy. Add 2 ¼ cups (315g) flour; mix. Transfer ¾ of the dough to pan; press into bottom; chill. Rub remaining dough and remaining ¼ cup (35g) flour into large crumbles; refrigerate. Make the filling: combine butter, brown sugar, syrup, and sweetened condensed milk in a 2-qt. heavy saucepan. Cook, stirring, over medium-high heat until thick and creamy and the mixture pulls away from the sides and bottom of the saucepan, 8–10 minutes. Pour over dough; scatter crumbles over top. Bake until golden, 25–30 minutes (mine needed 30). Let cool. Cut into bars.