Preheat oven to 350°F (175°C). Line a 9x13-inch metal baking pan with parchment paper, leaving an overhang on the long sides to create a sling. Lightly grease or butter the parchment, especially in the corners.
In a medium bowl, whisk together the all-purpose flour, granulated sugar, and 1/2 teaspoon fine sea salt. Add the cold cubed butter. Using a pastry cutter, two knives, or your fingertips, cut or rub the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-size bits and holds together when pinched.
2 cups all-purpose flour, 1/2 cup granulated sugar, 1/2 teaspoon fine sea salt, 1 cup unsalted butter
Pour the shortbread mixture into the prepared pan and press it firmly and evenly into the bottom, paying attention to the edges and corners (a flat-bottomed measuring cup works well). Bake for 15–18 minutes, or until the edges are just turning light golden while the center remains pale. Leave the oven at 350°F (175°C).
While the crust bakes, whisk the eggs in a large bowl until well combined but not frothy. Add the corn syrup, packed light brown sugar, melted butter, vanilla extract, and 1/2 teaspoon fine sea salt. Whisk until the mixture is smooth and glossy and the sugar is mostly dissolved. Stir in the pecans until they are evenly coated with the mixture.
3 large eggs, 1 cup light corn syrup, 1 cup light brown sugar, 2 tablespoons unsalted butter, 1 1/2 teaspoons pure vanilla extract, 1/2 teaspoon fine sea salt, 2 1/2 cups pecans
As soon as the crust comes out of the oven, give the pecan mixture a quick stir and carefully pour it over the hot shortbread crust. Use a spatula to spread the pecans into an even layer so that every bar will have plenty of nuts.
Return the pan to the oven and bake for 25–30 minutes, or until the filling is set around the edges and the center only barely jiggles when the pan is gently shaken (like firm gelatin, not liquid). You may see caramel-like bubbles forming around the edges; this is normal.
Transfer the pan to a cooling rack and let the bars cool completely in the pan, at least 2 hours, so the filling can firm up. For the cleanest slices, chill the cooled pan in the refrigerator for 30–60 minutes before cutting.
Use the parchment sling to lift the entire slab out of the pan and onto a cutting board. With a long, sharp knife, cut into about 24 small bars or 12–18 larger bars, wiping the knife clean between cuts for neat edges.
Serve the pecan pie bars at room temperature on a dessert tray, with coffee, or alongside a scoop of vanilla ice cream.