Heat oven to 350°F. Grease 9-inch pie plate.

Combine sugar, butter, and water in a medium saucepan. Cook over medium heat, stirring occasionally, just until mixture boils. Remove from heat. Immediately add 1 1/3 cups chocolate chips; stir until melted. Add eggs; beat with a spoon until well blended.

Stir together flour, baking soda, and salt; add to chocolate mixture, stirring until well blended. Stir in vanilla and remaining chocolate chips; pour into prepared pie plate.

Bake 25 to 30 minutes or until almost set. (Pie will not test done in the center.) Cool.