Traditionally used to decorate Christmas cookies (or as the mortar for your gingerbread house!).
Makes about 4 cups of icing, enough for an average-sized gingerbread house and more than enough for one batch of cookies.
2 large egg whites
4 cups powdered sugar
1 teaspoon vanilla extract or lemon juice
Food coloring if desired
1. Beat the egg whites in a stand mixer (or in a large bowl with an electric hand mixer) until frothy.
2. Gradually add the powdered sugar a half-cup or so at a time with mixer on low speed, fully incorporating each addition before adding more.
3. When all the sugar has been added, add the vanilla extract or lemon juice and turn the mixer to high. Continue to beat until the icing forms stiff, glossy peaks.
4. If you want multiple colors of icing, divide the icing into smaller containers and mix in the food coloring. If not using right away, cover tightly and refrigerate for up to 3 days.
For my family (including my healthy kids who are 11 and 13), I use this recipe as written, and make a point of choosing pastured eggs for this. Salmonella tends to be less prevalent in hens that are not cooped up in factory egg-laying operations, but of course there's no guarantee than any given chicken or egg is not infected.
If you have small children, or someone in your house is immune-compromised, you may want to substitute pasteurized egg whites. I haven't used them myself (when my kids were little, I never seemed to plan these projects ahead of time, so just decorated with other things), but from what I understand you can swap them in and get the same results. There is also a powdered egg white product, but I have no idea how that might affect the recipe. (If you're using the powdered kind, you should probably google "how to make royal icing with powdered egg whites" or something.)
A stand-mixer can be super useful for big baking projects! I'm including a link to the one I use, in case you're in the market for one. They're pricey, but if you do a lot of cake or cookie baking, they definitely speed the whole project up so you can make bigger volumes at a time. Hubby bought me mine about 15 years ago, and I've been super grateful to have it for big projects like bake sales, or birthday cakes for both kids at once (a week apart!).
If you don't envision yourself doing bigger-scale baking projects very often, you can definitely get by with a hand mixer. I'm including a link to my favorite one - it came with several attachments for different jobs, and a handy little canvas bag to store them all in.