How to cook
Mix the milk, butter, sugar, cocoa and vanilla over low heat until the butter and chocolate melt. Once this happens, remove the mixture from the heat and set it aside. In a large bowl, whisk the eggs. Add the flour and baking powder. Mix to get a solid blend and then add the cooled chocolate.
Stir everything and pour it into a greased tray. Optionally, add coarsely crushed walnuts. Bake at 356°F (180 °C) in a preheated oven until ready.
While waiting, prepare the glaze. On low heat, mix 4 tablespoons of cocoa, butter, water and sugar. Beat to thickening. Remove from the heat and let it cool. Cut the finished baked cake into diamond shapes and pour the glaze on top, while spreading it with a spoon.
Consume either hot or cold, whichever way you prefer.