This four-ingredient recipe come from Chicago pastry chef Mindy Segal's book Cookie Love. Her biggest tip: Shortbread is forgiving, but for best results, pay attention to temperature. Start with chilled butter, and make sure the dough is always cool (like marble) but not cold. If it cracks when rolled, let it warm up slightly; too sticky, pop it back in the fridge for a bit.
Shortbread dough should be the temperature of marble--cool but not ice-cold. Start with chilled butter, refrigerate between steps and work quickly. If the dough sticks to the rolling pin or cutters, stop and transfer everything to the fridge for 10 minutes. If it cracks, let it rest at room temperature for 10 minutes. Shortbread is forgiving, but it doesn't like to be rushed.