Cream shortening and margarine. Add cocoa powder, salt, and vanilla and beat thoroughly. Add powdered sugar 1 cup at a time mixing well between additions, alternating with the water. Scrape down bowl between additions. Start with 3 Tbsp of water and check consistency before adding more.
This will give stiff consistency icing. For thinner consistency, add additional water 1 tsp at a time until desired consistency.
To measure by weight (the preferred method):
4 oz shortening 4 oz margarine 1 lb powdered sugar, sifted
This is a light cocoa frosting. It is not cloyingly sweet or overly chocolaty. For a deeper chocolate flavor, increase the cocoa powder to 3/4 cup.
You can use any kind of stick margarine that is safe for you. Do not use tub or spread margarine as the water content is too high. You can use all shortening if necessary, but the flavor will be flatter and it may require additional liquid to get to the correct consistency. Be sure to add a generous pinch of salt if using unsalted margarine or all shortening.
If you do not have a milk allergy, butter may be used.
Butter and Margarine: Butter is a dairy product made from cow’s milk. Margarine typically contains milk or soy, but there are milk-free and soy-free versions available.
Corn Substitutions: Corn is a common ingredient in products. Starch, modified food starch, dextrin and maltodextrin can be from corn. Consult with your physician to find out which corn derivatives you need to avoid. Many corn-free options are available in the US. Find out more about corn substitutions.