Preheat oven to 300 degrees F. Spray a 9x13 baking dish with nonstick spray. Set it aside.
Cube the bread into ½ inch cubes. Roughly chop the pecans. Add bread and pecans to a sheet pan and toast in the oven for about 15 minutes, watching carefully so they don't burn.
Remove the sheet pan from the oven and increase the temperature to 350 degrees F.
Chop the butternut squash into ½ inch cubes, apples, onion, celery, and leeks. Place the leeks in a colander and wash them thoroughly, as they are usually very sandy and dirty.
Heat the olive oil in a large skillet over medium heat. Sauté the onions for about 5 minutes. Add in the leeks, apples, celery, salt, and pepper. Stir to combine. Cook until they start to soften, about 8 to 10 minutes.
Remove the apple and onion mixture from the heat. In a large bowl, combine toasted bread, pecans, dried cranberries, herbs, and the squash. Add the cooked apples, onions, leeks, and celery
Toss to combine all of the ingredients in the bowl. Pour in chicken broth, gravy, and eggs. Toss again to coat everything.
Scoop out into the baking dish, cover with foil, and bake in the oven for 25 to 30 minutes.
After the time is up, increase the oven temperature to 400 degrees F, remove the foil, and cook for another 25 to 30 minutes, or until the stuffing has set, is golden brown, and no longer wet on top.