Blanquette: Preheat oven to 375 degrees. Season rear legs with salt and pepper, dust with super-fine flour. Lightly brown in butter. In a large rondeau over medium heat, lightly brown bones, all vegetables and aromatics and sweat slowly. Place rabbit legs on top of vegetables and deglaze with Riesling. Bring to a slow simmer and reduce until all of the liquid has nearly evaporated. Add the chicken stock 2/3 of the way up the meat. Cover and braise in oven until tender, approximately 45 minutes to 1 hour and 15 minutes.
Spaetzle: In a small mixer, blend egg yolks, flour, fromage blanc, nutmeg and salt and pepper. Whisk slowly to form a paste. Whisk in milk slowly until mixture is slightly heavier than a pancake batter. Pass through a small colander into the boiling water until the spaetzle comes to the surface. Remove spaetzle to a baking sheet lined with a paper towel. Once spaetzle is dry, heat vegetable oil in a saute pan until hot. Add the spetzele and cook until crisp. Remove spaetzle from pan onto a paper towel lined baking sheet. Drizzle with white truffle oil and sprinkle with salt and pepper.