Heat 3 tablespoons olive oil and 3 tablespoons butter in a large skillet or saucepan.
Add 2 large onions(chopped finely), 4 ribs celery(diced), 1 cup carrots(diced), and 6 ounces bacon(chopped into small pieces) and fry them together for 5 minutes, stirring once or twice.
Stir in the 2-4 cloves garlic and 1 pound lean ground beef and cook, until the meat is no longer pink. Lower the heat and continue cooking for a further 10 minutes, stirring occasionally.
Increase the heat to medium, stir in 2 tablespoons tomato paste and 1 tablespoon all-purpose flour, and cook for 1 or 2 minutes.
Stir in 15 ounces can crushed tomatoes and 2/3 cup beef stock, and bring to a boil, stirring.
Season the 1 pound spaghetti pasta with salt and pepper and 1 tablespoon Italian Seasoning.
Cover, and simmer for 45 minutes, stirring occasionally.
Let the sauce reduce, then pour over freshly cooked pasta.