Servings: 1 (9- x 13-inch) pan

2 1/2 sticks cold unsalted butter, cut into cubes 2 ½ sticks cold unsalted butter, cut into cubes
1/4 cup plus 2 tablespoons light brown sugar ¼ cup plus 2 tablespoons light brown sugar
1/4 cup plus 2 tablespoons granulated sugar ¼ cup plus 2 tablespoons granulated sugar
2 1/2 cups all-purpose flour sifted with 1/2 teaspoon kosher salt 2 ½ cups all-purpose flour sifted with ½ teaspoon kosher salt
4 tablespoons unsalted butter 4 tablespoons unsalted butter
1 cup light corn syrup 1 cup light corn syrup
1 cup dark brown sugar 1 cup dark brown sugar
5 large eggs 5 large eggs
1 ½ teaspoons pure vanilla extract 1 ½ teaspoons pure vanilla extract
1 ½ teaspoons kosher salt 1 ½ teaspoons kosher salt
2 cups pecan halves 2 cups pecan halves

Preheat the oven to 350°F. In the bowl of a stand mixer fitted with the paddle, cream the butter with the sugars at medium speed for 2 minutes. With the mixer at low speed, beat in the sifted flour-and-salt mixture.
Line a 9- x 13-inch baking pan with parchment paper, allowing 2 inches of overhang on the two long sides. Transfer the dough to the pan and press it over the bottom and 1 ¼ inches up the side all around. (You can cover the dough with plastic wrap and press with the bottom of a measuring cup.) Be sure the corners are not too thick. Refrigerate until firm.
Bake the crust for 30 to 35 minutes, until golden brown; halfway through baking, use the back of a spoon to smooth the sides and corners of the crust. Transfer the pan to a wire rack and let the crust cool before filling.
In a medium saucepan, melt the unsalted butter over moderate heat. Remove the saucepan from the heat and whisk in the light corn syrup and dark brown sugar, then whisk in the eggs until thoroughly blended.
Whisk in the vanilla extract and salt; stir in the pecans halves until combined.
Pour the pecan filling into the prebaked crust and bake for about 35 minutes, until the filling is set. Transfer the pan to a rack and let cool completely. Cut into bars and serve.