The Best Shortbread Ingredients: 1 lb (2 cups) unsalted (or "sweet") butter (DON'T use margarine!) 1 cup powdered (or icing) sugar 4 cups sifted white flour OR 1 cup sifted rice flour and 3 cups sifted white flour. Preparation: Cream the butter, and gradually work in the sugar. Make sure that it's blended well, but don't overwork it or let the butter become oily. Gradually work in all of the flour. Place the dough in the fridge for about half an hour (not too much longer, or it becomes unworkable and the taste starts to change). Preheat your oven to 375F Roll out the dough on a lightly floured surface. If making cookies, roll it 1/4" or less thick; if making shortbread rounds, roll it about 1/2" to 3/4" thick. Cut out your desired shapes and place them on a baking sheet. For cookies: Bake for 5 minutes at 375, then turn down oven to 300 and cook for an additional 10-15 minutes, checking frequently. For rounds: Bake for 10 minutes at 375, then turn down oven to 300 and continue cooking for 45 to 60 minutes, checking frequently. Rounds are done when the edges of the rounds are nicely golden but not browned. Cut into wedges while still warm.