Preheat oven to 350 with a rack in the middle of the oven. Liberally season the roast inside and out with salt and pepper. Mix remaining ingredients and rub the roast inside and out with the mixture. Let sit at room temp for 30 minutes. Place in oven on middle rack and cook for one hour. Make stuffing.
Sausage and Fontina Stuffing
In a large sauté pan or cast iron skillet, sear the sausage on medium high heat, breaking up the pieces with a wooden spoon. When the sausage is cooked through, remove from pan and set aside. Discard all but 1T of the fat from the pan. When cool enough to handle, chop sausage into small pieces. They don’t need to be uniform. Heat pan over medium heat and add shallots for a few minutes until translucent. Add mushrooms and cook until they are soft and starting to get nice color. Remove from heat. Place the sourdough cubes into a baking dish. Add sausage, Fontina, mushroom shallot mixture and chopped thyme. In a separate bowl, mix cream, chicken stock and eggs together. Pour over the bread mixture and combine with your hands until well mixed. It should feel quite wet; add more chicken stock if the mixture feels too dry.
Remove the roast after one hour and pour the stuffing into the middle of the roast. Place roast with stuffing back in the oven and continue to cook for another hour or until 140 internal temperature. Temp roast at the thickest part of the meat just inside the roast behind the bones. Let cool and carve between the bones and serve.