Soak the raisins in the port wine for at least 1 hour or, preferably, overnight.
Preheat oven to 375ºF (190ºC) degrees.
In a skillet, heat 1 tablespoon of the olive oil. When hot, sear the chicken breasts on one side until golden brown. Turn the chicken over and brown the other side. Transfer to an ovenproof dish. Bake in the oven for 10 minutes.
In the meantime, in the skillet, heat the remaining 1 tablespoon olive oil. Add the shallots,
garlic and carrots and sauté them for 2 minutes. Add the mushrooms and sauté them for 2 minutes. Add the vinegar and reduce until almost dry. Stir in the raisins and their soaking liquid. Cook until the liquid is reduced by half.
Add the cream, nutmeg, cayenne, and cornstarch mixture. Cook for 2 more minutes, but do not bring to a boil. Adjust the seasoning with salt and pepper.
Spoon the sauce onto serving plates, set a chicken breast on top, spoon two tablespoons of sauce on top and garnish with the carrots, and fresh herbs.