Preheat the oven to 300° F. Cut the bread into ¾ inch cubes and toss with the olive oil and garlic. Season to taste with salt and pepper. Bake, occasionally tossing until golden brown, about 35 to 45 minutes, until toasted. (The actual time will depend on the bread you use; pay close attention towards the end of the toasting time.)
Increase the oven temperature to 350° F.
Meanwhile, melt the butter in a large pan over medium-high heat. Add the sausage and cook for 7 minutes, breaking up the meat with a wooden spoon.
Add the onion, celery, thyme, and rosemary to the pan. Season to taste with salt and pepper and cook for 8 minutes, scraping up the browned bits.
Place the bread, sausage, and vegetable mixture in a large bowl. In another bowl, whisk together the eggs, broth, and fresh parsley. Pour the mixture over the bread and toss to combine.
Coat a 9 x 13-inch baking dish with cooking spray. Spread the stuffing in the pan. Spray a piece of foil with cooking spray and place the foil over the stuffing, sprayed side down.