Preheat oven to 400º F. Find a standard size loaf pan and set aside.
In a large skillet, heat olive oil over medium heat, and add onions, celery, apples, and garlic. Sauté for about 15 minutes, until the onions are very tender.
Season the vegetables with fresh sage and rosemary, and sea salt and black pepper. Stir to combine and release the oils from the herbs. *After transferring the vegetables to the chicken mixture, do not wash the pan. Leave it with the seasoning to make the chicken gravy in!
In a large mixing bowl, combine the ground chicken with the sautéed vegetables and apples, and the dijon mustard and cayenne pepper. Use a spoon (or your hands!) to fully mix the vegetables into the chicken.
Add the chicken mixture into the loaf pan, and smooth out the top.
Cover the meatloaf with foil, and bake for 40 minutes. Remove the foil and continue baking another 15 minutes to brown the top. Remove from the oven and allow to rest for 10 minutes prior to slicing and serving.