The thing that makes this shortbread so special is an easy initial step of dry toasting the flour before it gets added to the cookie dough. The flour will take on roasty toasty flavors in the oven, which translates to a nuttier, more interesting cookie, with very little extra effort at all. You can shape these sandwiches however you like - any shapes will work – just cut out a little window in half of them if you want the cream filling to peak through the top.