Crunchy cracked caramel balances a smooth butterscotch custard filling in this simple, satisfying tart.
For the crust:
- 2 cups (9 oz.) all-purpose flour
- 8 tbsp. chilled unsalted butter, cut into 1/2-inch cubes
- 1⁄2 tsp. kosher salt
- 1 large egg, lightly beaten
For the filling and caramel:
- 4 oz. high-quality white chocolate, finely chopped
- 8 tbsp. unsalted butter
- 1 cup packed light brown sugar
- 1 tsp. kosher salt
- 6 tbsp. crème fraiche
- 3 tbsp. Lyle's golden syrup or light corn syrup
- 4 large eggs
- 3⁄4 cup granulated sugar
Make the crust: In a large bowl, combine the flour with the butter and salt and rub with your fingers until crumbly. Pour in the egg and 3 tablespoons ice-cold water and stir until a dough forms. Shape the dough into a ball, wrap in plastic wrap and refrigerate for 30 minutes.
While, the dough chills, make the filling: Place the white chocolate in a small bowl and melt the butter in a small saucepan. Pour the butter over the chocolate, let stand for 1 minute, then stir until smooth. In a large bowl, whisk the brown sugar with the salt, crème fraiche, syrup, and eggs until smooth. Pour the butter-chocolate mixture into the custard and whisk until evenly incorporated.
On a floured work surface, roll the tart dough until 1⁄4-inch thick. Fit the dough into the bottom and side of a 11-inch tart pan with removable bottom, trimming the edges, and pierce the dough with the tines of a fork. Freeze the tart dough for 30 minutes.
Heat the oven to 350°. Remove the tart pan from the freezer, place directly in the oven, and bake until the dough is golden brown on the bottom, about 15 to 20 minutes. Whisk the butterscotch filling again until smooth then pour it into the tart pan, while it’s still in the oven, until the filling just comes to the top of the crust (you may have about 1⁄4 cup of the filling leftover). Reduce the oven temperature to 300° and bake the tart until the filling is set but still wobbly in the center, about 50 minutes. Transfer the tart to a rack, let cool completely, then refrigerate until chilled, at least 2 hours or overnight.
About 30 minutes before you’re ready to serve the tart, make the cracked caramel. Place the granulated sugar in a small nonstick skillet over high heat and cook, shaking and swirling the pan occasionally, until the sugar dissolves into an amber caramel. As soon as the last bit of sugar dissolves, remove the tart from the refrigerator and quickly pour the caramel over the top of the tart, tilting the tart to allow the caramel to form an even layer. Let the tart stand for 10 minutes to allow the caramel to harden, then crack the caramel with the back of a spoon or knife and cut into wedges to serve.