Egg yolks are the sunshine of baking. Golden, beautiful, and full of flavor. They also are very effective in emulsifying and thickening creams and batters. There are three things that are very important to know about egg yolks: 1) More and more often, the proportion of yolk to white is less than it has been over the past decades. This means that a recipe dependent on many yolks in order to set or have the proper consistency may be significantly short on yolks if you go by just the specified number. I've found, occasionally, that when I measure or weigh 6 yolks I need to add as many as 3 more to have the needed amount. So be sure either to measure or weigh the yolks. I list them on every recipe and if you're using other people's that don't, make a little index card with measurements or weights to put up in your kitchen as a reminder. 2) If egg yolks are combined with sugar and allowed to sit they will crust over, dry out on the surface, and result in lumps in the cooked or baked product. If you need to separate eggs ahead of using them, either spray the yolks with nonstick cooking spray or if using oil in the recipe that will be added together with the yolks, simply store the yolks in the container with the oil. 3) If you have extra yolks and are not in the mood to make lemon curd! you can freeze them but only if you stir in some sugar which will maintain their texture. Be sure to mark on the container how much sugar you added so you can subtract it from the recipe when you're ready to bake with them. I use 1/2 teaspoon sugar per yolk which is enough to keep them from being sticky when defrosted.