Begin thawing the turkey in the refrigerator or in a cooler kept at 38 degrees F.
Combine the vegetable stock, salt, brown sugar, peppercorns, allspice berries, and candied ginger in a large stockpot over medium-high heat. Stir occasionally to dissolve solids and bring to a boil. Then remove the brine from the heat, cool to room temperature, and refrigerate.
Early on the day or the night before you’d like to eat:
Combine the brine, water and ice in the 5-gallon bucket.
Place the thawed turkey (with innards removed) breast side down in brine. If necessary, weigh down the bird to ensure it is fully immersed, cover, and refrigerate or set in cool area for 8 to 16 hours, turning the bird once half way through brining.
Preheat the oven to 500 degrees F.
Remove the bird from brine and rinse inside and out with cold water. Discard the brine.
Place the bird on roasting rack inside a half sheet pan and pat dry with paper towels.
Combine the apple, onion, cinnamon stick, and 1 cup of water in a microwave safe dish and microwave on high for 5 minutes. Add steeped aromatics to the turkey’s cavity along with the rosemary and sage.
Tuck the wings underneath the bird and coat the skin liberally with canola oil.
Roast the turkey on lowest level of the oven at 500 degrees F for 30 minutes. Insert a probe thermometer into thickest part of the breast and reduce the oven temperature to 350 degrees F. Set the thermometer alarm (if available) to 161 degrees F. A 14 to 16 pound bird should require a total of 2 to 2½ hours of roasting.
Let the turkey rest, loosely covered with foil or a large mixing bowl for 15 minutes before carving.
Cook and drain pasta according to package directions. Slice the mushrooms ⅛ of an inch thick and sauté in 2-3 tablespoons of the butter, along with sliced onion, and chopped garlic until lightly browned. Combine the remaining butter with flour and add chicken broth, stirring over low heat until thickened. Add the cream, salt, pepper, sherry, and garlic powder.
Divide the sauce in half. And one half of the chicken meat, and half of the mushrooms and cooked pasta. Butter a casserole dish and turn the pasta mixture into the casserole leaving a well in the center of the pasta.
Turn remaining cooked chicken half into the center of the pasta mixture. Top with Parmesan cheese, and bake uncovered at 400°F for 20 minutes.
Optional: may also top with butter to breadcrumbs and grated cheddar or American cheese.