Drain the juice from the tomatoes and reserve. Crush the tomatoes with your fingers in a bowl.
Heat the olive oil in a skillet until it shimmers. Add onions and crushed red pepper (and basil, if using dried). Cook until the onions become transparent, but not browned.
Raise the heat to medium high and add both the canned and cherry tomatoes, plus 1/2 cup of the reserved juice. Bring to a medium boil and hold it there, stirring every thirty seconds or so, for about three minutes. Lower the heat to a simmer and cook for ten minutes, stirring every now and then.
Add the parsley, fresh basil, salt, and--if you think the sauce is too thick--a little more juice from the tomatoes. Cook another three to five minutes. Add the cooked penne to the pan and toss to coat with the sauce. Serve with grated Parmesan cheese.
