Preheat the oven to 350°F (175°C). Grease a 9x13 inch baking dish.
In a bowl, mix together the softened butter, flour, and granulated sugar until well combined. Press the mixture evenly into the bottom of the prepared baking dish.
Bake the crust in the preheated oven for 15 minutes, until lightly golden.
While the crust is baking, whisk together the brown sugar, beaten eggs, corn syrup, chopped pecans, and vanilla extract in a bowl.
Pour the pecan filling over the pre-baked crust and spread it out evenly.
Bake in the oven for an additional 30 minutes, or until the filling is set and lightly browned.
Allow the bars to cool completely in the baking dish before slicing into squares and serving.