Preheat the oven to 375°F, and drizzle 1 tablespoon of olive oil into the bottom of an 8x8 or 9x13-inch baking pan or casserole dish.

Place the bell peppers, onions and garlic into the pan, and drizzle the remaining oil on top then sprinkle on the chili flakes and salt.

Bake for 25 minutes then flip the peppers over, toss the garlic and onions, and bake for 20 more minutes.

In the meantime, boil the pasta according to package directions. Drain and reserve 1 cup of pasta water. Set aside

Once cooked, add all the veggies to a large blender along with the pasta water and blend until smooth.

Pour in the heavy cream and pulse a couple more times. 

Pour the sauce into the pot that you used to boil the pasta. Turn the heat to low-medium and bring the sauce to a simmer. Add the parmesan cheese, and cook for at least 20 minutes or until the sauce has reduced a bit and started to thicken.

Add the cooked pasta back to the pan and toss to combine then serve with additional shredded parmesan cheese and freshly chopped parsley if desired.