I have a reliable powdered sugar recipe for buttercream frosting, but I wanted to stay as close as possible to Dorie Greenspan's original directions for the March Daring Bakers Challenge. I decided to try several substitutions for the egg, so I made three 1/4 batches using corn starch, Ener-G Egg Replacer, and a vegan gelatin. You can see the results above.
The corn starch and egg replacer made glazes instead of frosting. The gelatin started out looking like other two, but after having the margarine added and being whipped, its structure and texture changed completely. The resulting frosting is silky smooth and spreadable with a slippery mouth feel. After tasting it, my husband compared it to a meringue. Success!
Update: Sorry it's taken me so long to get the recipe up!
1 C sugar
1/2 C boiling water + 10g packet of vegan gelatin
3 sticks (12 oz) slightly softened dairy free margarine, not all the way to room temp (I prefer Earth Balance Buttery Sticks)
1/4 C fresh lemon juice
1 tsp vanilla extract
Dorie's original recipe calls for whisking egg whites together with the sugar in a double boiler. Since the gelatin, which replaces the egg whites, is being mixed directly with boiling water, the gentle method used on the egg whites is unnecessary. One word of caution: if there are any lumps in the gelatin, be sure to pound or sift them out, or there will be lumps in the frosting.
Mix the gelatin and boiling water, then stir in the sugar, making sure it is completely dissolved. (Don't be put off by the appearance. Yes, it looks like a bowl full of snot, but persevere anyway!) Using a hand mixer or the whisk attachment on a stand mixer, beat the mixture on medium speed until cool, about five minutes. Change to a paddle attachment if using stand mixer, and beat in the margarine one stick at a time until smooth. Increase the mixture speed to medium high and beat until thick and very smooth, about six to ten minutes, or longer if necessary. This is when you will see the dramatic change in the texture . Reduce speed to medium and gradually add the lemon juice and vanilla extract. Keep the resulting frosting covered and refrigerate any extra. It will handle much better at room temperature.