My favorite pasta sauce - mild tomato flavor and mildly creamy, slightly thick, and so flavorful on ravioli or any other pasta.
Heat oil or butter in a medium-sized saucepan.
Add onion, carrot, celery, tomatoes, salt, and sugar. Bring to a quick boil and then reduce heat to low. Simmer, partially covered, for 1 hour.
Puree in blender or food processor and return to saucepan.
Stir in cream or half and half (if using) and warm over low heat.
Taste and add additional salt, if necessary.
Serve over pasta with shredded/shaved Parmesan cheese, if desired.