Simmer for about an hour until the sauce is reduced by three-fourths.
Preheat oven to 200°C.
Heat butter and oil in a sauté pan over high heat. Seasonchicken breasts with salt and pepper and sauté until the first side is browned—about a minute. Turn and brown other side. Place pan in oven until chicken is almost cooked. Remove from oven, tent and set aside for 5 minutes.
Strain sauce and add truffles to sauce. Heat gently.
Slice breasts on the bias and arrange in a fan shape on individual serving plates. Top with sauce.