Preheat oven to 350º.
Cream butter and sugars.
Add egg and vanilla and mix till combined.
Add dry ingredients and fold in chips.
Press cookie dough into the bottom and sides of a 9 inch tart pan.
Bake for about 20 minutes till nicely browned (I tried 25 mins and it was a drop too crisp. It will puff up and fill the pan). As soon as you remove it from the oven, press the bottom flat with the back of a spoon to create room for the caramel.
Cool completely.