Ready to bring this dish to life? Follow these simple steps:

1. Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking dish with a bit of olive oil to prevent sticking.
2. Cook the spaghetti according to package instructions until al dente. Drain and set aside.
3. In a large skillet over medium heat, add the olive oil. Sauté the onion and bell pepper until they are soft and fragrant, about 5 minutes.
4. In a large mixing bowl, combine the cream of mushroom soup, cream of chicken soup, chicken broth, and sour cream. Stir in the sautéed vegetables, shredded chicken, garlic powder, salt, and pepper.
5. Add the cooked spaghetti to the bowl and toss everything together until the noodles are well coated with the creamy mixture.
6. Transfer the mixture to the prepared baking dish. Sprinkle the top with cheddar and Parmesan cheeses.
7. Bake in the preheated oven for 30 minutes, or until the cheese is bubbly and golden brown. Let it cool for a few minutes before serving.

My tip? Make sure to taste the sauce before adding it to the spaghetti. Adjust the seasoning to your taste; after all, cooking is about making the dish your own!