Preheat your oven to 400 degrees. Toss the sweet potatoes, brussels sprouts and onion with the bacon drippings, marjoram, honey and salt and pepper in a large bowl and transfer to a rimmed backing sheet. Top with Italian sausages (poke a couple holes in them with a knife) and bake for 15 minutes.
Meanwhile, mix together the chicken marinade ingredients and coat the tenderloins with it. Set aside.
Give the veggies a stir and flip the sausage. Add the chicken tenderloins on top of the veggies and return to the oven. Cook for an additional 10-15 minutes or until the chicken has reached 165 degrees and the sweet potatoes and brussels sprouts are fork tender.