Preheat the oven to 350F then line a baking sheet with parchment paper and set aside.
In a large bowl or in the bowl of your stand mixer cream the butter and sugar together for 3-4 minutes until light and fluffy.
1 cup butter, 1 cup granulated sugar
Add in the egg, the vanilla extract, and the milk and mix for another 2-3 minutes. Mix in the flour, cornstarch, and baking powder. Stop mixing as soon as the flour mixture disappears.
½ teaspoon salt, 1 tablespoon vanilla extract, 2 eggs, 4 cups flour, 2 tablespoon corn starch, ⅛ teaspoon baking powder, 1 tablespoon milk
On a parchment-lined surface, sprinkle some flour, add your cookie dough, and sprinkle some more flour on top then roll the dough to about ⅓" then cut out the cookies using your favorite cookie cutter, bake the larger cookies for 9-10 minutes and the smaller ones for 6-7 minutes.
Let the cookies col down fully before decorating!