Preheat your oven to 350°F and line a 9x13-inch baking pan with parchment paper. In a large bowl, combine flour, powdered sugar, and salt. Cut in cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs with some pea-sized pieces remaining.

Press the mixture firmly into the prepared pan, creating an even layer that extends slightly up the sides. The crust should feel compact under your palms. Bake for 18-20 minutes until the edges are lightly golden but the center still appears pale.

While the crust bakes, sprinkle chocolate chips evenly over the hot crust as soon as it comes out of the oven. Let it sit for 2-3 minutes, then use the back of a spoon to gently spread the softened chocolate into an even layer.

In a medium bowl, whisk together eggs until well beaten and slightly frothy. Add corn syrup, brown sugar, melted butter, and vanilla extract, whisking until the mixture is smooth and glossy.

Fold in the chopped pecans, making sure they're evenly coated with the syrup mixture.

Pour the pecan filling over the chocolate-topped crust, using a spatula to spread it evenly to all corners. The filling should completely cover the chocolate layer.

Bake for 25-30 minutes until the filling is set around the edges but still slightly jiggly in the center. The surface should be golden brown and no longer wet-looking.

Remove from oven and cool completely in the pan, about 2 hours, before cutting. Use a sharp knife wiped clean between cuts for clean squares.