Prep Ingredients: Cube bread, chop veggies, and shred cheese.
Cook Sausage: Brown sausage in olive oil, seasoning it with rosemary or Italian seasoning.
Sauté Veggies: Cook onion, garlic, bell peppers, mushrooms, and spinach in the same skillet until tender.
Assemble: Layer bread in a greased 9x13-inch baking dish, followed by sausage, veggies, and cheese.
Prepare Egg Mixture: Whisk eggs, milk, salt, and pepper. Pour evenly over the layered ingredients.
Refrigerate: Cover and refrigerate for 1 hour or overnight to let flavors meld.
Bake: Preheat oven to 375°F (190°C). Bake uncovered for 40–45 minutes, or until the top is golden brown and the center is set.
Serve: Let it rest for 5–10 minutes, then slice and enjoy!