Coat the bottom of a large pot with olive oil.
Turn the flame on the burner to medium/low heat.
Add the diced onions and the red crushed pepper to the pot. Cook until the onions are translucent.
Add the tomato paste to the pot and stir it around to wake it up.
Add the sauce puree from the blender to the pot and stir. Lower the flame a bit on the burner.
Then add 1/2 cup of cold water to the blender vessel, turn the blender on to clean the inside of it of the remaining sauce puree. And put that mixture into the pot and stir.
Thin the sauce puree out a little more by adding the remaining amount of cold water to the pot.
The consistency of the sauce should be slightly thicker than a chicken soup.
Next add the dried or fresh basil, salt, and ground black pepper.
Cook and reduce the sauce down over simmer low heat stirring occasionally for at least 2 hrs. This will help develop the flavor of the tomatoes further.
After the 2 hrs, add the sugar to the pot and stir. Taste the sauce for salt. If it needs more add it.
Cook for another hour on simmer low heat stirring occasionally.
Once the sauce has reduced and thickened, add the pint of heavy cream.
Stir until the cream is heated through. Do NOT let the cream come to a boil.
Turn off the heat and let your pot of sauce rest as you start the process of boiling pasta.