Vanilla Cutout Cookies that Don't Spread

Preheat the oven to 375 degrees, and line baking sheets with parchment.

Cream the butter and sugar, just until smooth and combined (try not to whip in any air).

Mix in the eggs until incorporated.

Add the flour**, cornstarch, and salt, and mix on medium low speed.  The mixture will seem very dry and sandy at first, but after 3 to 5 minutes in the mixer it should gather itself into a ball and pull away cleanly from the sides of the bowl.

Stir in the vanilla. (If you do not have an electric stand mixer with a paddle attachment, you may have to knead the dough by hand to fully bring it together.)

Working with a managable amount at a time, roll the dough out between 2 sheets of parchment paper, to a thickness of 1/4-inch to 1/2-inch.*

Cut into shapes, peel away from the bottom sheet of parchment carefully (see the video below), flip onto the prepared baking sheets, and bake until set around the edges but still a bit soft in the centers (approx. 9 to 12 minutes for 2 1/2-inch, 3/8-inch thick cookies).

Cool completely, then decorate with royal icing.