Preheat oven to 400°F (200°C).
Prepare the vegetables: Peel and chop the sweet potato into small cubes. Roughly chop the bell peppers, carrots, zucchini, and shallot. Add everything to a large baking sheet in a single layer. You may need two baking sheets if too crowded.
Season and roast: Drizzle with olive oil and season with salt, pepper, garlic powder, and Italian seasoning. Toss to coat. Roast for 25 minutes, or until the vegetables are soft and lightly caramelized.
Blend the sauce: Let the vegetables cool slightly then transfer the roasted vegetables to a blender. Add the tomato sauce, water, Parmesan cheese, and Better Than Bouillon. Blend on high until smooth and creamy, stopping to scrape down the sides as needed. *Caution: the sauce will be hot, allow an opening at the top to vent the steam.
If the sauce is too thick, add a splash of water and blend again. Taste and adjust salt and pepper as needed.
Serve with your favourite pasta, or let cool and store in the fridge or freezer for easy meals later.