Line two to three cookie sheet pans with parchment paper and preheat the oven to 350°F.

Add the flour, cornstarch, baking soda, and baking powder to a bowl and whisk to combine.

In the bowl of a stand mixer, fitted with the paddle attachment, cream the butter and 1 ½ cups of sugar on medium speed for 2 minutes until smooth and fluffy. Scrape down the sides with a rubber spatula.

Add the eggs and vanilla and beat until combined, about 20 seconds.

Add the flour mixture to the mixing bowl and mix on low speed for 30 seconds until just combined and no streaks of flour remain. Give the dough a stir by hand with a spatula to make sure it’s mixed completely.

In a shallow dish, add the remaining ⅓ cup of sugar. Scoop 1 1/2 tablespoon sized portions of cookie dough and roll into balls. Roll the dough balls in the sugar until coated.

Place the cookies on a sheet pan, 2” apart for spreading. 

Using two fingers or the flat bottom of a drinking glass, flatten the centers of each cookie.  Sprinkle the tops with a little more sugar–this is where you sprinkle on colored sugar if using.

Bake the cookies one sheet pan at a time at 350°F for 10-12 minutes until puffed in the center and the edges have set. The cookies should have little to no color around the edges.

Remove the cookies from the oven and let cool on the sheet pan for 5 minutes before transferring to a wire rack.