Beat butter and sugar till creamy. Add in eggs one by one beat well. Combine watermelon juice, watermelon puree,milk, vanilla essence add to the creamed mixture beat well. Sift flour, baking powder and salt and fold in to the mixture. Pour the batter into a greased tray and bake at 180 degrees for 35-40 minutes and cool them completely.
Beat butter till foamy add in sifted icing sugar beat well add in watermelon pulp and salt beat well. Do icing over the cake.