cream:
.5 cup margarine 
1 1/3 cup sugar
sift:
3 cups flour
3 tsp. baking powder
3/4 tsp. salt

mix dry ingredients into creamed mixture alternately with 2 cups liquid
(soymilk or water). Add 1 Tbsp. vanilla.
Beat 2 minutes.   Bake in 9x13 pan for 30 minutes at 350 degrees.

icing:
combine in medium saucepan with a whisk:
1 cup cold water
5 Tbsp. flour
cook over medium heat , whisking constantly until thick and smooth.
dont burn it.  cool completely by setting in pan of cold water.
cream until sandy:
1 cup sugar
3-6 Tbsp. margarine
1 tsp. vanilla
pinch of salt
3 Tbsp. cocoa (optional)
whip creamed mixture into the cool flour mixture until well blended and fluffy, then spread on the cake. If the frosting separates, reheat while whipping
constantly. then refrigerate until cool.

*note: many margarines have dairy. the quickest way to check is to look for
the kosher symbol on the front of the package. if it says K-d it has dairy
but if it says K-parve it doesnt.