Preheat the oven to 180C/350F. Line a large baking sheet with parchment paper.
In a large mixing bowl, mix together your softened butter with powdered sugar, until completely combined. Then, gently fold in the flour and mix very well, until a thick dough remains. Push the dough together to form a smooth ball.
Using your hands, form 12 balls of dough and place on the lined sheet. Press down on each one into a cookie shape, and if desired, use a cookie stamp to form a pattern.
Bake the cookies for 15-17 minutes, or until the edges begin to go golden brown. Remove from the oven and allow cookies to cool on the sheet completely.
Notes
TO STORE: Shortbread cookies can be stored at room temperature, in a sealable container or ziplock bag. They will remain fresh for up to 2 weeks. TO FREEZE: Place cookies in a ziplock bag and store in the freezer for up to 6 months.