In the bowl of a stand mixer fitted with a paddle attachment, cream together butter and sugars until fluffy and light in color-at least 5 min. Add egg and vanilla and blend in.
Combine flour, cornstarch, baking soda and salt. Add dry mixture to sugars. Mix on low to combine just until the flour disappears. Stir in the chocolate chips.
Using a standard-sized cookie scoop or tablespoon, drop dough onto a baking sheet. Bake for 8-10 minutes, until barely golden brown around the edges. (The tops will not brown, but do NOT cook longer than ten minutes.)
Let cool on the sheet for 3 minutes and then transfer to a wire rack to cool completely.
Recipe by Olivia Rose Cake Artistry at https://oliviarosecakeart.com/chocolate-chip-cookies/