Preheat oven to 375°F. Grease the pans.
1. Melt the butter. Add the vanilla and vinegar.
2. Sift the flour, sugar, cocoa, baking soda and salt into a separate bowl.
3. Add the cold water to the butter mixture, then pour into the dry ingredients and stir well.
4. Pour into two greased layer pans, or one large pan (10×14in). Bake 30 minutes, or until a toothpick comes out clean.
Icing #1 (quicker than a shop run): cream together the butter and honey. Add the vanilla — or the cocoa, for a chocolate icing — and enough milk to loosen. A little more milk thins it; a spoonful of powdered milk thickens it. Make it any colour you like.
Icing #2: cream the brown sugar and butter. Add the warmed milk and beat. Add icing sugar until it reaches the right consistency (up to 1 1/2 cups), plus vanilla or another flavouring.