Preheat oven to 350 degrees and lightly grease a 13 x 9 cake pan.
For crust: cream softened butter and brown sugar ONLY. Slowly stir in flour and mix together just until crumbly. Using fingertips, press into the bottom of lightly greased cake pan. Bake for 10 to 12 minutes or until lightly browned.
For filling: beat eggs together then add corn syrup, granulated sugar, melted butter, and vanilla.
Stir in chocolate chips and chopped pecans then pour over baked crust. Bake for an additional 25 to 30 minutes or until filling is set. Remove from oven and cool before serving.