Pre-heat oven to 350 ° F.

In medium bowl, mix together flour, sugar, baking soda, salt and chocolate chips.Add eggs and vanilla, stirring until blended.

Turn dough onto lightly floured surface; knead 8 to 10 times, adding a little more flour as needed.

Form dough into a log about 2-inches thick and 16-inches thick.

Place log onto baking sheet coated with non-stick spray. Bake 30 minutes; remove from oven and cool for 10 minutes.

Place log on cutting board and with a serrated knife, cut log diagonally into ½ inch slices, using a sawing motion. Place slices cut side up, on baking sheet.

Reduce heat to 325° F and bake for 10 minutes.

Turn slices over and bake an additional 10 to 12 minutes until golden. Centers will be slightly soft, but will harden as they cool. Remove to wire rack to cool.