In a large mixing bowl, beat the butter, granulated sugar, and powdered sugar together for 2–3 minutes until light and fluffy.
Add the eggs one at a time, mixing well after each addition. Mix in the vanilla extract.
In a separate bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients and mix just until combined. Do not overmix.