- 1 cup unbleached all-purpose flour
- 1/4 cup packed light brown sugar
- 2 teaspoons cornstarch
- 1/4 teaspoon salt
- 1/2 cup (1 stick) chilled unsalted butter, cut into 1/2-inch cubes
- 1 tablespoon ice water
- 1 large egg yolk
- 6 tablespoons (3/4 stick) unsalted butter, diced
- 1/2 cup packed light brown sugar
- 1 14- ounce can sweetened condensed milk
- 2 tablespoons dark corn syrup
- 1 teaspoon vanilla extract
- 6 ounces bittersweet or semisweet chocolate, chopped
- 3 tablespoons heavy whipping cream
- Flaked sea salt (such as Maldon)
For the crust:
Preheat oven to 350 degrees F. Coat an 8x8-inch baking pan with nonstick spray. Line with parchment, leaving enough to overhang, and spray parchment with nonstick spray.
Blend flour, sugar, cornstarch, and salt in food processor. Add butter. Pulse until coarse meal forms. Add 1 tablespoon ice water and egg yolk. Blend until moist clumps form. Press dough onto bottom (not sides) of prepared pan; pierce all over with a fork. Bake until golden, piercing if crust bubbles, 22 minutes. Cool completely.
For the caramel topping:
Melt butter in a medium saucepan. Add brown sugar, stir until dissolved. Whisk in milk, corn syrup, and vanilla and let come to a boil. Attach a clip-on candy thermometer to the side of the pan. Boil gently, whisking constantly, until caramel is pale golden and thick and thermometer registers 225 degrees F, about 8 minutes. Pour caramel over cooled crust, spreading evenly to the edges. Cool 15 minutes.
For the chocolate glaze:
Meanwhile, melt chocolate with cream in microwave in 15-second bursts, stirring until smooth. Be careful not to overheat. Spread chocolate over warm caramel; sprinkle with sea salt. Refrigerate until chocolate is set, at least 1 hour. Can be made 3 days ahead; cover and keep refrigerated. Cut dessert into long bars before serving.