This one is a never-fail for me:
1 cup nonhydrogenated margarine (I use Earth Balance)
3 1/2 cups powdered sugar, sifted if clumpy
1 1/2 teaspoons vanilla extract (or another flavor, if you choose)
Just beat together with a hand or stand mixer. Add a drop of soymilk if it's too stiff.
I tend to use my KitchenAid stand mixer because it's easier not having to hold the mixer. I think this makes about a quart, which should be more than enough to frost 24. Extra will keep in a closed container in the fridge; sometimes it stays in there for months if I forget I have it in there! It's also easy enough to cut the recipe in half if you plan to frost them lightly rather than heavily.
I do a lot of baking and cake decorating. I love this buttercream for pareve from the Wilton foods website. If you need it to be really white (margarine makes it a little yellow), go on the wilton website for other options.
* 1/2 cup solid vegetable shortening
* 1/2 cup (1 stick) butter or margarine softened (I like earth balance)
* 1 teaspoon clear vanilla extract
* 4 cups sifted confectioners' sugar (approximately 1 lb.)
* 2 tablespoons milk or coffee rich.
Makes: About 3 cups of icing.
This is only marginally different from the recipe I posted, which actually originally include the liquid (milk/coffee rich for you; I used parve, less chemical, soymilk) , but I found that so much liquid made the frosting far too wet and drippy, so I now leave it out entirely, and am always surprised that others do use it and are still able to spread and even pipe the resulting frosting. When I included that extra 2 tablespoons of liquid, there was no way to pipe it, it was that loose.