Combine butter and milk in a large pan, stir over heat until butter is melted. Remove from heat, stir in essence and castor sugar, then sifted flour and cocoa. Spread mixture into greased ovenproof dish (6 cup sized). Sift brown sugar and extra cocoa over mixture, gently pour over boiling water. Bake in moderate oven for about 40 minutes.
Best served hot.
—Zamperoni Family