Heat oil and butter in a Dutch Oven over medium high heat until the butter is melted and has stopped foaming.
Add onion, celery, and garlic and cook for 5 minutes, stirring often.
Sprinkle with Italian seasoning and red pepper flakes, and stir in tomato paste. Cook for 1 minute.
Add the ground beef, and cook until the moisture is evaporated and the meat is brown, about 10 minutes.
Add tomatoes, and bring to a boil. Reduce to a simmer and cook, stirring occasionally, for about 40 minutes.
Stir in the Parmesan cheese, salt, and pepper. Cook until the cheese is melted, about 2 more minutes.