Bring a large pot of salted water to a boil and cook the spaghetti according to the package directions until al dente. Drain and set aside.
2. Prepare the Sauce:
While the pasta is cooking, heat a large skillet over medium heat. Add a little butter or oil and sauté the diced onion until softened, about 5 minutes.
Add the minced garlic and cook for another minute until fragrant.
Stir in the cream of mushroom soup, diced tomatoes (drained), chicken broth, and milk. Stir until well combined and heated through.
Season the sauce with Italian seasoning, paprika, salt, and pepper to taste.
3. Combine Chicken and Pasta:
Add the shredded chicken to the sauce and stir to combine. Let the chicken heat through, about 3-5 minutes.
Add the cooked spaghetti to the sauce and mix well, ensuring the pasta is fully coated.
4. Bake the Chicken Spaghetti:
Preheat your oven to 350°F (175°C).
Pour the chicken spaghetti mixture into a greased 9×13-inch baking dish.
Top with shredded cheddar cheese and grated Parmesan cheese.
Drizzle the melted butter over the top of the cheese.
5. Bake:
Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly, and the top is lightly golden brown.
6. Serve:
Remove the chicken spaghetti from the oven and let it cool for a few minutes before serving.
Garnish with fresh herbs (like parsley or basil) or more cheese if desired.