It depends on the dessert. Flan ins't going to lend itself well to making it "fun to look at". And for some occasions, elegent is what is needed. Comical can be especially fun for the young at heart if the event isn't formal . And for fun, you don't need to stick to just desserts. Pancakes lend themselves to creativity. I've made them in the shape of Micky Mouse, Holloween ghosts, smiley faces, flowers, etc. I've made meatloaf shaped like a volcano, complete with a crater oozing a "lava" looking sauce on top of a landscape comprised of refried beans for the ground, and brocoli and cauliflower fowerettes for the trees. Carrot sticks make great little buildings, all to be engulfed by the hot lava.
Miniature pumpkins become cooked jack-o-lanterns and can be filled with sweet or savory fillings. Picture a carved pumpkin filled with spaghetti sauce, with cooked angel hair pasta coming out of the top, like hair.
You can be creative with all kinds of foods. We even made a jello mold in a bullet-shaped cake pan, and inserted a Barby Doll into it, to the waist. The jello became the skirt for the doll, with the pointy side up of course. So get creative. The only limit is your imagination.
Seeeeeeya; Goodweed of the North