Simple yet elegant birthday cakes are perfect for classy adult birthday parties. From plain chocolate to fruit-and-cookie topped, our sophisticated birthday cakes for adults, plus ideas for birthday cake toppers and cupcakes, will wow party guests of any age. The best way to make someone's birthday the BEST BIRTHDAY EVER is to bake them a kick-ass cake. Here's how. 35 Amazing Birthday Cake Ideas. Looking for the perfect adult birthday cakes? Do It Yourself Cake, Design Your Own Edible Image, adult birthday cake smash sign.