Preheat oven to 400 degrees F. Slowly heat clarified butter in medium pan,. Stir in flour and cook for 2 or 3 minutes over moderate heat. Add tomato paste and slowly stir in wine. Add bouquet garni and simmer gently for 30 minutes.
Add ham to sauce and season with salt and pepper. Add snails and simmer on low heat for 10 minutes; they will pop out of their shells. Mix in truffle.
Remove snails and shells from sauce, and discard herbs sachet. Place snails in their shells and top with sauce. Bake 5 minutes, until sauce bubbles.