In a pyrex pudding bowl, place the margarine. Microwave for 1 minute on high or until it is melted. Add the granulated sweetener, plain flour, cocoa powder and soy milk to the bowl. Beat until it is all smooth. Sprinkle the combined brown vegan sugar and cocoa powder on top of the mixture. Pour the boiling water over the top. Microwave for 17 minutes on medium power. Stand for five minutes before serving. You can also cook this in a conventional oven, if you prefer. Serve with soy icecream or soy custard.