Pappardelle is traditionally served with a sauce made from game, but chicken makes a delicious substitute in this richly flavored sauce. To freeze the sauce, prepare up to sautéing the mushrooms. Cook and blend in the mushrooms shortly before serving.
Heat in a large Dutch oven over low heat:
      3 tablespoons extra-virgin olive oil
Add:
      2 ounces salt pork, diced
      1 medium onion, finely chopped
      1 carrot, peeled and finely chopped
      1 celery stalk, finely chopped
Cook, stirring occasionally, until the vegetables are softened and beginning to brown, about 8 minutes.  Add to the Dutch oven:
      1 pound boneless chicken thighs, diced
Season with:
      Salt and ground black pepper to taste
Increase the heat to medium and brown on all sides, about 5 minutes. Stir in and cook until almost evaporated:
      1/2 cup dry white wine
Stir in:
      1 cup chicken stock
      1 28-ounce can whole plum tomatoes, drained and chopped
Reduce the heat to low and simmer, partially covered, until the chicken is tender, about 1 1/2 hours. Sprinkle with:
      6 fresh sage leaves, chopped
      Salt and ground black pepper to taste
Melt in a medium skillet over medium heat:
      3 tablespoons butter
Add and cook, stirring, until browned:
      8 ounces mushrooms, wiped clean and halved
      Salt and ground black pepper to taste
Add the mushrooms to the sauce.