In a mixer, cream butter, sugar, and vanilla (if using) together.

Add the cornstarch and flour and mix until crumbly. Then, stop using the mixer and pour the crumbled flour onto a floured surface.

Knead the crumbles into a dough, which should only take about a minute.

Cut dough into half to allow for more workable dough. Take one portion and roll out to a ¼ inch thick dough.

Line cookie sheets with parchment paper. Use a cookie cutter and cut out shapes and place shapes on cookie sheet (see notes). Use scrap dough and roll out again and again until there is little left. Do the same for second portion of dough.

Place pans in the fridge to chill for an hour (up to overnight).

When ready to bake, preheat oven to 350 ℉. Bake cookies for about 5 minutes and pull out of oven to sprinkle with sugar (if doing). Just a little dusting should do. Place back in the over for another 5-7 minutes, or until just beginning to brown around the edge.

Pull out of the oven and allow the cookies to cool on a rack for about 5 minutes or until cool. Store in an airtight container.