Preheat oven to 350°.
In a large mixing bowl, cream the butter, sugar, vanilla, and egg.
Add the salt, cornstarch, and 1 cup of flour. Mix until well combined.
Add flour 1/4 cup at a time, mixing between, until the dough comes together and begins cleaning the sides of the bowl. You may not need all of the flour.
Turn the cookie dough out onto a floured surface. Roll to approximately 1/4 inch thickness, then use cookie cutter to cut out shapes.
Line a cookie sheet with parchment paper or a silicone mat. Place the cut out shapes on the lined sheet.
Bake the cookies at 350° for 8-10 minutes.
Place the cookies on a wire rack to cool. Cool completely before decorating.