Nut crescents (also known as Viennese crescent, butterballs, and Mexican wedding cakes) do not get the respect they deserve. Often the first to be tossed out in a pile of leftover Christmas cookies, they appear stale, dry, floury, and flavorless, except perhaps for a pasty layer of melting confectioners' sugar. But when these cookies are well made, they can be delicious: buttery, nutty, slightly crisp, slightly crumbly, with a melt-in-your mouth quality. We wanted to develop a recipe that would put them back in their proper place, as the perfect accompaniment to a cup of coffee or tea. The ratio of butter to flour in almost all of the recipes we looked at was the same: 1 cup to 2 cups, and this is what worked for us, too. We tried three kinds of sugar: granulated, confectioners', and superfine. The last resulted in the melt-in-your-mouth texture we wanted. In determining the amount (a modest 1/3 cup), we had to remember that the cookies would be sweetened once more by their traditional roll in confectioners' sugar. While some recipes argue in favor of coating the cookies while they're still warm from the oven, we found that this created exactly the pasty coating that we wanted to avoid. We recommend letting the cookies cool to room temperature before finishing them off with confectioners' sugar. If you make these cookies more than a day ahead of time, roll them again in confectioners’ sugar, shaking off the excess, before serving. We found that pecans and walnuts worked equally well in our recipe. An equal amount of toasted and skinned hazelnuts can be used if you prefer. Almonds can be used raw for cookies that are light in both color and flavor or toasted to enhance the almond flavor and darken the crescents. You will need just 1¾ cups of whole blanched almonds in this recipe; add ½ teaspoon almond extract along with the vanilla extract to boost the almond flavor. We like the delicate crescent shape but if you prefer you can roll the dough into balls to make Mexican wedding cakes; use one tablespoon of dough per cookie. The baking time will be the same.