Cook spaghetti until al dente. and reserve some pasta water for further cooking.
Heat olive oil in a large skillet. Brown the Italian sausage, then remove it from the pan. Cook sliced chicken until golden and fully cooked.
Add onions and bell peppers to the skillet. Sauté until slightly soft. Stir in minced garlic and cook briefly.
Pour in marinara sauce and crushed tomatoes. Add Italian seasoning, red pepper flakes, salt, and black pepper. Simmer for 10 minutes.
Return sausage and chicken to the skillet. Add cooked spaghetti and toss everything together until coated in sauce.
Mix in parmesan cheese and fresh herbs. Add reserved pasta water if required.
Serve hot in a sizzling skillet with extra parmesan cheese and fresh basil on top.