02In a large skillet, heat grapeseed oil over medium-high heat. Saute mushrooms and red onions with thyme sprigs, stirring frequently, until mushrooms are caramelized, about 7 minutes. Remove from heat, stir 4 tablespoons butter into hot mushrooms and discard thyme. Set mushrooms aside.03Use remaining butter to coat a 3-quart baking dish. In a large mixing bowl, whisk eggs, one cup cream and 2 cups chicken broth together. Add bread and stir until coated evenly. Fold in sweet potatoes, mushroom mixture and remaining herbs. If bread cubes seem dry, add more cream and chicken broth. Season with salt and pepper. Spoon stuffing into baking dish and bake until golden brown and cooked through, about 45 minutes.