These are a Christmas institution as far as I'm concerned. I got the recipe out of the Washington Post about a decade ago and have been making them ever since. They're a little finicky but basically easy—very different and very pretty. Easy for people to eat, too, as they’re finger food. The recipe seems to be all over the place on the web, so I guess it doesn't belong to anyone in particular. There's been one problem with it in that the tarts have tended to stick to the pan, although I haven't had this problem with the other fillings I list. So when I make it I use rounds of parchment paper cut to be a little smaller than the size of the mini-tart pans. Then I just flatten out the dough using the paper as a guide. This may seem like a lot of work, and it is, but it's a lot less work than having them stick and then having to pry them out of the pans. And think of the efforts people make with other Christmas treats! So these aren't so bad. Once I figured out what to do it went pretty fast.
Sugar content for these is pretty low because they're so small. My best guess is that they have 6 grams per tart, which surprised me. So you could, in theory, have four of these and not go over 25 grams. But that's assuming that you're not loading up your plate at a party with lots of other treats. Everything counts!
The recipe says, “Never be tempted to put more than three cranberries in each one cup; one berry too many can force a tiny fruit eruption. For some reason, this recipe does not work well in regular-size muffin tins or as a large tart.” So you will need to get a mini-muffin pan—it will have 24 cups, and will work best if it’s nonstick. (Actually, you need to buy several pans, as I discuss below. But if my saying that scares you off of this recipe, just buy one for now.) You'll see in the picture that I used four cranberries if they were really small.
Preheat oven to 350 degrees.
Using a food processor, combine the crust ingredients. Dough should be fairly moist and come together easily. Chill the dough for an hour or so, as otherwise it's very soft. Then you can use the method outlined above to make the tartlet shells, or you can press the dough into the pans with your fingertips.
TWO NOTES: It works best if you can make the dough have a bit of a rim sticking up above the pan so that you guard against overflows (also mentioned below in connection with not overfilling). I've also found that these are crisper and nicer if the dough is very thin; if you do the fingertip method of pressing the dough into the pans you'll have to be sure that there aren't any holes. That's another reason for using the parchment paper. If you make the dough very thin you're going to have more than you need for 24 tarts, so that's why I suggested that you buy more than one pan. I personally don't think that this recipe is worth making unless you mass-produce them; I usually make 96, that is, enough to fill four pans. But I make only three times the dough and the filling. They come out great using those proportions. (So if you triple the recipe you'll end up needing nine ounces of cream cheese, which of course means that you'll have to cut off one ounce from another eight-ounce bar. What a pain!) I would recommend that you use a small digital kitchen scale to measure out the dough. The absolute thinnest crusts will require 3/8 ounce; more sturdy ones will require 1/2 ounce.
Using an electric mixer at medium speed, combine the egg, sugar, butter and vanilla, mixing well. Stir in the nuts. Place 3 cranberries in each cup and spread some of the nut mixture over the cranberries, filling each cup so that the cranberries are covered.
YET ANOTHER NOTE: I have found from making this recipe many, many times that it’s best not to overfill the cups with the egg/sugar mixture. The filling will bubble up and spread outside the crust, and you’ll have a mess. The recipe actually makes a little bit too much of the filling, and it’s tempting to try to use it all up on the 24 tarts, but don’t do it! There’s no real way you can make less filling, since it calls for one egg. Yet another reason to make my 96-tart version.
Variation: You can use chopped apples instead of cranberries, adding some cinnamon or apple pie spice to the filling mixture. Bake for the same amount of time. I'm not posting this as a whole separate recipe since everything else remains the same.