Yield: 3 dozen cookies
Preheat oven to 375° F
Cream together butter and sugars. Add in vanilla extract.
Add in egg and egg yolk.
Add in flour, baking soda, salt, and cornstarch. Mix throughly
Stir in chocolate chips.
Drop by spoonful onto ungreased baking sheet.
Bake for 9-12 minutes. Immediately remove from baking sheet and cool on wire rack.