Among the many things I find myself homesick for, one of the tip-top rankers has to be Rainbow Cookies (aka TriColor Cookies, 7 Layer Cookies.) These are hands-down my favorite cookie of all time, though they bear a much closer resemblance to Petite Fours than cookies.
When I was a kid, we would stock up on these on each of our trips to NYC since you basically can't find them outside of there. After moving out of NY, I was so sad that I couldn't get them anymore. I searched for a recipe for them on the internet for years and finally 3 appeared all at once. The one I go off of is on the Smitten Kitchen site, which I can always trust for a good recipe.
Now they are a bit of a new Christmas tradition for me, mostly because out here the fools who stock grocery stores only sell almond paste (the main ingredient) at Christmas time. This makes me very sad. I made two batches this Christmas, which yields a crap-load of these guys, but they still disappeared at an alarming rate. I had to ration off a small portion for a belated Christmas gift exchange that I am soon to have with my sisters-in-law. I will miss these until next year.