FOR THE CRUST

1 1⁄2 cups flour
1⁄4 cup plus 1 tablespoon dutch-process unsweetened
cocoa powder
1⁄4 teaspoon. kosher salt
10 tablespoons unsalted butter, cubed and softened
1⁄2 cup plus 2 tablespoons. confectioners' sugar
2 egg yolks, room temperature
1⁄2 teaspoon pure vanilla extract
FOR THE CARAMEL

1 1⁄2 cups sugar
3 tablespoons light corn syrup
1⁄4 teaspoon kosher salt
6 tablespoons water
6 tablespoons unsalted butter
6 tablespoons heavy cream
1 tablespoon sour cream
1 teaspoon pure vanilla extract
FOR THE GANACHE

1⁄2 cup heavy cream
4 oz. Scharffen Berger Bittersweet Chocolate, finely chopped
Vanilla Fleur de Sel for garnish (optional)