Heat a large nonstick skillet over medium-high heat. Add olive oil and garlic and cook 30 seconds. Add cooked veggies and tomatoes. Cook, stirring a few times, about 1 minute, 30 seconds. Spoon into pasta pot. Stir grated cheese into the half- and-half mixture. Add to pasta and gently stir in parsley until all ingredients are combined. Allow to stand for 5 minutes. Shave Parmesan on top, if desired.