There are two on the Food 52 Blog, which I find to be pretty reliably delicious. One is flourless and you dust it with powdered sugar and the other is made with rice and oat flours instead of wheat flour and is frosted. The latter is an Alice Medrich recipe, which is an excellent recommendation for any dessert recipe.
There's also one on the Serious Eats website which is another pretty reliable site. That one uses coffee liqueur and is topped with a raspberry puree.
It is important when making chocolate cake recipes that call for cocoa to use the kind of cocoa specified. If it asks for "Dutch Processed" cocoa, make sure that's what you use. If it asks for "natural" cocoa, use that. "Dutch processed" cocoas are marked on the box. Sometimes Dutch processed cocoa boxes will say "alkali processed" instead.