Cream 1/2 cup butter and sugars. Add eggs and blend in a large mixing bowl. Sift the flour, bicarb soda, salt, cinnamon and nutmeg together. Add to sugars and egg mixture. Add vanilla and oats mixture, blend well.
Pour batter into a 20x30cm pan.
Bake in a preheated (180 degrees C) oven for 30-40 minutes.
To make icing: Mix together 6 tablespoons melted butter, 1 1/2 cups brown sugar, 3/4 cup evaporated milk, coconuts, nuts and 1 teaspoon vanilla.
Pour this coconut concoction over the hot cake.
Put cake under grill and watch close so nuts don't burn, about 5-10 minutes. Serve hot or let cool.