Thinly slice all vegetables and sausage so they are about the same thickness and add to a large bowl.
Toss in olive oil, italian seasoning, garlic salt, and pepper. (I never really measure how much seasonings I use, just sprinkle on a hearty amount and make sure all the vegetables get coated. Taste one raw and see how you like the seasoning level and add more if desired).
Spread your veggie mixture on a cookie sheet and roast at 375 degrees for 45 minutes or until veggies are just tender, but not soggy. Rotating halfway through.
If desired, sprinkle on cheese with ten minutes left so it has time to melt.
Store leftovers in fridge in an airtight container for 7 days.