Take a cake mixing bowl and put in the butter. Cream it well. Then add the sugar and keep mixing. Gradually add the well beaten eggs and the self raising flour, earlier sifted with the baking powder a couple of times. Put in the banana mash, the rawa and the chopped cashewnuts. Mix lightly. Then pour into a greased baking dish. Bake in a moderately hot oven for about 25-30 minutes till the top becomes slightly brown.