Brown the Italian sausage. Heat a large skillet over medium heat. Add the Italian sausage and cook, stirring frequently and breaking it into smaller pieces, until evenly browned and fully cooked.
Drain excess grease. Carefully drain and discard the excess fat from the cooked sausage to prevent the sauce from becoming oily.
Add the tomatoes. Pour the tomato sauce and diced tomatoes into the skillet with the browned sausage. Stir until evenly combined.
Season the sauce. Add the bay leaves, Italian seasoning, garlic powder, dried basil, dried oregano, salt, and black pepper. Stir gently to distribute the seasonings throughout the tomato mixture.
Simmer the sauce. Reduce the heat to medium-low and allow the sauce to simmer gently for at least 1 hour, stirring occasionally to prevent sticking. Continue simmering longer if desired for deeper flavor.
Prepare the pasta water. Near the end of the sauce's cooking time, bring a large pot of lightly salted water to a rolling boil.
Cook the spaghetti. Add the spaghetti and cook for approximately 8–10 minutes, or until tender but still firm to the bite. Follow the package directions as needed.
Drain the pasta. Drain the spaghetti thoroughly and transfer it to a large serving bowl. Remove and discard the bay leaves from the sauce.
Combine the spaghetti and sauce. Add the cooked spaghetti to the sausage tomato sauce and toss gently until the pasta is evenly coated.
Serve hot. Divide the spaghetti among serving bowls and enjoy while warm.
