In the several months (and added pounds) required to perfect these cookies, we found guidance in a recipe we stumbled upon for "Buckingham Palace Shortbread" which was reportedly enjoyed by the Queen with her tea. We had to make a few modifications to get a dough that would survive the rigors of our old fashioned, hand-cranked cookie press, but the result is the most buttery and delicate cookie possible. For the coating, we wanted something very flavorful and unexpectedly tart to meet the "intense flavor" standards of our products. Messy like a good powdered sugar donut, the taste is, at first, shockingly tart, but then quickly succumbs to the buttery melt in your mouth cookie at its heart. Lemon is decidedly the most popular flavor. (When feeling particularly indulgent, topping with a dollop of lemon curd is amazing!)