This is very intricate free hand nail detailing so Im posting it only as mere inspiration. However, you can use the same idea using negative space down the middle and use water decals or stamping to get the same general effect as the pic.
These chocolate bowls are genius! Who doesn& want to eat out of a chocolate bowl? There are step by step pictures for making them on Bakerella. Chocolate Bowls regular sized balloons chocolate cooking spray wax paper Blow up balloons about.