Preheat the oven to 350°F. Line a cookie sheet with parchment paper. Set aside.

In the bowl of a stand mixer, combine the butter and sugar the cream until smooth.

Add in the 2 whole eggs, 2 egg yolks, vanilla, corn starch, baking soda, baking powder, and salt. Combine well, scraping dow the sides and mix again.

Add in the flour. Mix until the dough balls up and pulls away from the sides. Make sure there are no hidden dry pockets in the bottom of the bowl.

Use a 2 ounce cookie scoop to form cookies into balls.

Place the sprinkles in a shallow bowl. Roll the dough balls in the sprinkles until all the sides are covered. Slightly flatten into a disk shape, and place on the prepared baking sheet.

Bake for 10-12 minutes - just until the edges are set and very slightly browned. The cookies should have a soft, chewy center. If you over bake them, they'll be harder and crispier.

Allow to cool and enjoy.