Preheat oven to 350 degrees F. Mist a 9x13-inch casserole dish with nonstick cooking spray; set aside.
Place cubed bread on a baking sheet and bake for 20 minutes, stirring once.
Meanwhile, pierce potatoes with a fork and microwave on high on a microwave-safe plate for 8 minutes. Let stand 5 minutes to cool slightly; peel potato, and cut into ½-inch cubes.
Heat a small nonstick skillet over medium heat. Add oil to pan; swirl to coat. Add sausage to pan; cook 6 minutes or until browned, breaking up with a wooden spoon as it cooks.
Place bread, sweet potato, half of sausage, and half of cheese in a large bowl.
Combine milk, spices, and eggs in a bowl, combining with a whisk; pour over bread mixture, and toss gently to combine. Let stand 5-10 minutes before transferring to the prepared casserole dish.
Sprinkle with remaining sausage and cheese. Cover with foil lightly coated with cooking spray. Bake for 1 hour, removing the foil with 10 minutes of bake time left. Let stand 5 minutes. Serve with maple syrup, if desired.