In a food processor, cut 2 sticks (1/2 lb.) butter into pieces.
Add 1/2 cup sugar.
Add 2 cups flour (& pinch of salt if using unsalted butter)
Pulse together until the batter starts to ball together.
Dump the batter into a large bowl.
Knead batter with hands until it becomes smooth and the consistency of clay.
Pat into flat disk shape and center on cookie sheet. With hands and fingers, begin patting, massaging, pushing the batter outward to spread and cover the cookie sheet, leaving 1 inch from the edge of the sheet. (This is the hard part! Yes, I've tried a rolling pin [marble], but only if the batter is still reasonably cool, otherwise you end with a good portion of the batter on the rolling pin!) Just keep patting and pushing-you'll see how it starts to spread under your guidance! The spread batter should be about 1/2-inch thick all over when done.
With a fork, poke lots of holes all over the spread batter.
Bake at 300 degrees F for 1 hour, but start checking at 40 minutes and remove from the oven when it's a light golden brown.
Place on a wire rack and generously sprinkle sugar all over the top.
When slightly cooled (20-30 minutes), cut shortbread into desired square sizes. (It's important to cut shortbread while still warm-ish-if you wait till it's cooled it has a tendency to break up when trying to cut it due to its crispness.)
While the first batch is baking, start all over-repeating the above steps and remaining ingredients-to make the second batch.
When completely cooled, using a spatula, move shortbread squares to desired plate or container.
Serve anytime with anything! Keep well covered/sealed-it's best when crispy but never bad regardless of condition!!!