Preheat oven to 350 degrees.
Combine butter and sugar in a large bowl. Cream well.
Add the eggs, one at a time, mixing well after each egg.
Stir in flour, vanilla, and pecans.
Sprinkle the chocolate chips over the bottom of the pie shell.
Cover with filling.
Bake 40-45 minutes.
Serve warm with whipped cream or ice cream.