Preheat oven to 325° F. Place rack in lower position.
Pat turkey dry with paper towels.
Crush garlic cloves with salt to make a paste. Mix the softened butter with the garlic paste. Rub butter and garlic mixture all over the outside of the turkey as well as inside the skin (especially at the breast) and inside the cavity. Sprinkle freshly ground pepper and about half a teaspoon of cinnamon all over turkey.
Set a rack inside a large roasting pan. Place turkey breast side up on the rack. Tuck tips of wings under turkey. Place a few pieces of carrots, celery and onion inside the turkey's cavity along with some fresh herbs. And then spread the remainder of the vegetables and herbs around the turkey in the pan. You can add the neck, heart and gizzards to the pan and tie the legs together with kitchen twine. Pour 1 cup of water into pan.
Place the roasting pan with the remaining drippings and aromatic veggies and herbs over medium heat, add broth and scrape the bottom of the pan. Simmer for a few minutes. Strain the broth into a large measuring cup or heatproof bowl.
In a large saucepan, over medium-high heat, melt butter and add flour. Cook until flour and butter mixture (roux) starts to colour. Add reserved broth, whisking to remove any lumps. Let gravy simmer over medium heat, taste and adjust salt and pepper to taste.