Chop, mince and dice all of the ingredients as listed.
Place a large skillet over medium heat. Add 1 tbsp of the oil and brown the sausage, breaking it up as it cooks, about 5-7 minutes. Transfer the sausage to a bowl and set aside.
In the same skillet, add the remaining oil and saute onion, garlic and mushrooms (optional) for 2-3 minutes, or until onions are transparent. Season with the Herbs de Provence and salt and pepper to taste.
Add the spinach (it will be a full pan's worth), and saute until the spinach wilts, about 3-4 minutes.
Add the onion/spinach mixture to the bowl with the sausage. Also add the bread cubes and Parmesan, mix everything together and then set aside.
Grease a 9"x13" baking dish with spray oil (or rub with 2 tbsp butter).
In a large liquid measuring cup, use a hand blender to mix the eggs, half-and-half, salt and pepper, until thoroughly blended.
Pour the egg mixture over the sausage/spinach/bread/Parmesan until everything is well mixed.