DIY Forth of July Fireworks Cake Recipe and Tutorial. Use ready made mix and frosting or make it from scratch. Easy cake to make with the how-to at Bird on a Cake here. *To get the frosting super smooth take a knife or metal cake spatula and run it under really hot water and then go over the frosting with it (how do I know this? Cake decorating class which I was terrible at). *First seen at craftgossip here.