Add gelatin to stock. Heat slightly to dissolve gelatin. Cool over an ice bath until the stock starts to thicken.
Combine foie gras, stock, and cream. Chill until ready to use.
Coat the bottom of a ramekin with gelatin made from clarified stock. Decorate with herb leaves, such as tarragon, and a slice of truffle. Coat with another layer of gelatin. Add "mousse de foie gras" and refrigerate until firm.