Preheat oven to 400 degrees Fahrenheit. On a large roasting pan, arrange onion pieces, tomato halves, and red pepper halves. Drizzle with olive oil, sprinkle with salt, then toss to coat.
Roast veggies until browned on edges (red peppers may take longer than other veggies - just remove those from pan and set aside when done).
Once the red peppers are charred, remove from oven. Let cool then remove skins. While veggies are cooling, cook pasta and drain. Toss with a little olive oil so it doesn't stick once cooked.
In a large blender combine tomatoes, red peppers (skinned), and roasted onion. Add in 1 clove garlic (minced or grated) and blend until smooth. Add 1/2 c. cream to blender (can use coconut milk if you're not eating dairy), then add salt and pepper to taste. Cream until smooth.
Pour sauce over cooked pasta. Top with fresh parsley and Parmesan cheese, and cracked pepper if you'd like.