This isn't really a recipe, but its awesome so I'll post it anyways.
I love making Black Forest Cake like something fierce. It became even more of a favorite when my overachieving impulse kicked in a few years ago and I decided that it actually needed a black forest... or rather, a semi-sweet forest. This is a paragraph of a tutorial, but I hope you'll try it with some trees... or flowers or swirls or any design really. The options for this chocolate application really are endless.
You can melt your chocolate on a double boiler, or I like to do it the quick way... in a microwave. I put my chocolate in a completely dry plastic bowl and microwave it in 10 second intervals. I "whisk" it with a fork in between until its nice and smooth and creamy and pretty. For these particular trees, I printed out a few silhouettes but if you wanna free hand it, go for it. I used parchment paper and a piping bag to create my forest masterpiece... a freezer ziploc bag and plastic wrap works too. Make sure to keep your chocolate drawing on a flat surface especially when you finish piping and put it in the freezer for 5-10 minutes. After it has "set" and solidified in the freezer, take it out, peel off the paper, and quickly transfer to your cake. You'll want to keep your cake refrigerated until you serve it so that your chocolate stands upright and doesnt fold or melt.
That's it. Really.
You can make a quick black forest cake with chocolate rounds, cherry pie filling and whipped cream frosting. Fucking delicious.
Best of luck with your chocolatey art!