Preheat oven to 350F. CAKE: Combine the dry ingredients in a mixing bowl. Mix in the walnuts if using. Stir in the soy milk & mix until well blended. Spread the batter into an ungreased 8" baking tin. Set aside. SAUCE: Combine the cocoa powder & sugar. Pour the boiling water over the mixture. Stir well to ensure that it is all dissolved. Gently pour over the batter. Bake for 30 to 40 minutes, or until the cake tests done. Set aside to cool before serving. Recipe by Mark Satterly