Lightly oil two baking sheets.
I put a little oil on a paper towel and rub all over the pan surface.
Cream the butter and sugar together.
Add the oil and milk and mix well. Set aside.
In a large bowl add the two flours, cornstarch, baking soda and salt.
Add the wet ingredients to the dry ingredients and stir until just combined.
Stir in the vanilla and chocolate chips.
Do not overwork.
Loosely roll into balls and put on your cookie sheet. Flatten a bit. They do not spread much when baking. The dough makes about 36 cookies.
Bake in a 350° oven for 10 minutes.
Take out of oven to cool for 5 minutes.
Remove from pan and let cook on a rack.