Salted Caramel Tart

Ingredients

• 1 large egg yolk
• 1 tablespoon heavy whipping cream
• 1 1/2 cups (about 6 3/8 ounces) all-purpose flour, plus more for surface
• 2 tablespoons granulated sugar
• 1/2 teaspoon kosher salt
• 1/2 cup (4 ounces) cold unsalted butter, cut into 1/2-in. pieces
• 1 cup heavy whipping cream
• 1/4 cup (2 ounces) unsalted butter
• 1 teaspoon kosher salt
• 1 1/2 cups granulated sugar
• 1/4 cup water
• 1/4 cup light corn syrup
• 1 (3 1/2-ounce) 70% cacao bittersweet chocolate bar, chopped (about 3/4 cup)
• 1/2 cup heavy whipping cream
• Flaky sea salt (such as Maldon)

Steps

1. For the crust, whisk the egg yolk and cream together in a small bowl until combined, then set it aside. Combine the flour, sugar and salt in a food processor, about 10 seconds. Scatter the butter over the flour mixture and pulse until the butter looks like small peas, 10 to 12 pulses. Keep the processor running as you add the reserved egg yolk mixture; process just until a dough forms, about 1 minute. Place the dough on plastic wrap, wrap tightly and form a 6-inch disk. Refrigerate until firm, at least 1 hour or up to 3 days.
2. On a lightly floured work surface, roll the dough to a 12-inch circle about 1/8-inch thick. Move it carefully into a 10-inch round tart pan with 1-inch-tall sides and a removable bottom, pressing gently into the corners and fluted sides. Roll a rolling pin across the top to trim away excess dough. Keep those trimmings for patching holes, covered with plastic wrap and set aside. Gently push the crust sides upward to expose about 1/16-inch. Prick the entire crust with a fork's tines and freeze uncovered until firm, at least 30 minutes or up to 24 hours.
3. Preheat the oven to 350°F. Drape 2 layers of aluminum foil loosely over the crust and fill it with pie weights or dried beans. Set the pan on a large rimmed baking sheet and bake in the preheated oven until the crust is just set, about 25 minutes. Take out the foil and weights, using the reserved dough to patch holes if necessary. Bake at 350°F until the whole crust is golden and firm, 10 to 15 minutes. Take it out and cool completely in the tart pan on a wire rack, about 20 minutes.
4. Prepare the caramel filling while the crust cools. In a small saucepan over medium-low heat, warm the cream, butter and salt, stirring occasionally, until the butter melts, about 5 minutes. Remove from the heat and set aside. In a large saucepan over medium heat, bring the sugar, water and corn syrup to a boil while stirring constantly with a fork. Continue boiling over medium heat, swirling the pan often without stirring, until it starts turning golden and a candy thermometer reads 325°F, about 10 minutes. Turn off the heat and gradually whisk in the cream mixture, whisking constantly. Return to a boil over medium heat and boil without disturbing until the candy thermometer reads 235°F to 240°F, about 5 minutes. Pour the caramel into the cooled crust and let it cool completely at room temperature, about 1 hour, 30 minutes.
5. For the ganache, put the chocolate in a medium heatproof bowl and set aside. Bring the cream to a simmer in a small saucepan over medium heat, stirring constantly. Pour it hot over the chocolate and leave undisturbed for 5 minutes. Stir gently until melted and smooth, about 1 minute. Pour the ganache over the cooled caramel in the crust, spreading it evenly to cover the filling completely. Refrigerate uncovered until fully set, about 1 hour. Scatter flaky sea salt over it, slice and serve. If the tart has been refrigerated for longer than 1 hour, leave it at room temperature for 5 to 10 minutes before cutting.