Slice sausages lengthwise, leaving links attached along one side; lay flat in a large skillet. Cook over medium heat until browned and cooked through, flipping once.

Add ground beef, onion, garlic, and olive oil to the same skillet over medium heat; cook and stir until onion is translucent and beef is browned and crumbly. Drain all but 2 tablespoons drippings from the skillet. Stir in tomato sauce, tomatoes, oregano, salt, basil, bay leaf, and black pepper; simmer uncovered over low heat until flavors have blended, stirring occasionally.

Preheat the oven to 350 degrees F (175 degrees C).

Bring a large pot of lightly salted water to a boil. Cook spaghetti in the boiling water, stirring occasionally, until tender yet firm to the bite. Drain.

Stir spaghetti into sauce.