1. Gather ingredients: butter, powdered sugar, flour, optional vanilla extract, and cornstarch.
2. Soften butter to room temperature for easier mixing.
3. In a mixing bowl, cream the butter and powdered sugar until light and fluffy.
4. Add vanilla extract if using and mix until incorporated.
5. Gradually add flour and cornstarch, mixing until a soft dough forms.
6. Shape dough into a disk and chill for at least 30 minutes to help hold its shape.
7. Preheat oven to 325°F (163°C) while the dough chills.
8. Roll out dough and cut into desired shapes or form into a log and slice.
9. Place cookies on a parchment-lined baking sheet, spacing them slightly apart.
10. Bake for 12-15 minutes or until the bottoms are lightly golden brown.
11. Let cookies cool on the baking sheet for a few minutes before transferring to a wire rack.
12. Optional: Dip in melted chocolate or decorate with sprinkles if desired.
13. Store in an airtight container at room temperature for up to 5 days.
14. Freeze leftovers for up to 2 months for longer storage.
15. Enjoy or package for gifting and holiday cookie exchanges!