Heat the oven to 400° F.
Add the pecans to a cold, dry, large skillet or Dutch oven. Turn the heat on medium and cook, stirring occasionally, until the pecans are darker in spots and smell nutty, about 8-10 minutes. Remove to a cutting board and wipe out the skillet. Roughly chop the nuts and add to a large mixing bowl.
In the clean skillet, heat the oil over medium heat. Add the Italian sausage and cook, stirring occasionally and breaking it down into little chunks, until no longer pink, about 5-8 minutes. Use a slotted spoon to scoop the sausage into the bowl with the nuts, leaving the fat in the pan.
While the sausage is cooking, peel and dice the onion and sweet potatoes and dice the celery. After the sausage is removed, add the veggies to the pan along with the salt and saute, stirring occasionally, until the veggies begin to soften, about 8-10 minutes.
While the veggies are cooking, core and dice the apple (no need to peel). Once the veggies have begun to soften, add the apple, dried cherries and apple cider vinegar. Saute, stirring occasionally, until the apple begins to soften and the liquid is absorbed, about 5 minutes. Scrape into the bowl with the sausage.
In a small bowl or measuring glass, whisk the chicken broth and egg together. Add to the sausage and veggies along with the minced herbs and black pepper. Toss everything together until well combined and the liquid is somewhat absorbed.
Pour the mixture into an ungreased 8x8" / 2-quart baking dish and gently pat down so the top is evenly flat. Bake for 40-45 minutes, until baked through and the top has browned. Let rest for 10 minutes, then dig in!