Preheat the oven to 350°F.
Line a 9x13-inch baking pan with parchment paper or foil, leaving some overhang for easy removal.
In a large mixing bowl, beat the softened butter and granulated sugar until well combined.
Add the flour and mix just until a soft dough forms.
Press the dough evenly into the bottom of the prepared pan.
Bake for 18–20 minutes, or until the crust is lightly golden.
While the crust bakes, prepare the pecan topping. In a medium bowl, whisk together the brown sugar, corn syrup, melted butter, eggs, and vanilla until smooth and well combined.
Stir in the chopped pecans.
Pour the pecan mixture evenly over the hot baked crust.
Return the pan to the oven and bake for 30–35 minutes, or until the center is set.
Allow the bars to cool completely in the pan before cutting into 12 servings.