Heat your oven to 350 F and prepare two cookie sheets by greasing and lining them with parchment paper.
In a mixing bowl, whisk together the olive oil, both sugars, vanilla, and the egg until the mixture is smooth.
Fold in the cornstarch, baking powder, baking soda, salt, and flour using a spatula until everything is just combined.
Scoop out the dough with a 2-tablespoon measure and place the mounds on the cookie sheets, spacing them about two inches apart as they will spread.
Bake the cookies for around 10 minutes and then check: if they have developed prominent crinkles they are ready.
If not fully crinkled, continue baking an additional 2 to 4 minutes until they are puffy, cracked all over, and the edges turn a dark shade.
Remove from the oven and let the cookies cool on the sheets — they will flatten out as they cool down.
