Set your oven to $350^circ F$ ($175^circ C$). Grease a large 9x13 inch baking dish with butter or non-stick spray. Shred your chicken and set it aside in a large bowl.

Fill a large pot with water and add plenty of salt. Bring to a boil and cook the spaghetti until al dente. Drain the noodles and keep them warm for the next step.

In a separate large bowl, combine the mushroom soup, chicken broth, and sour cream. Use a whisk to ensure the mixture is smooth. This forms the base of your rich sauce.

Add the garlic powder, onion powder, dried thyme, salt, and pepper to the liquid. Stir well so the spices are evenly distributed. Smell the herbs; they add a wonderful earthy aroma.

Add the shredded chicken and the cooked spaghetti into the large bowl with the sauce. Toss everything together gently. Ensure every strand of pasta is covered in the creamy soup mixture.

Pour the chicken and pasta mixture into your prepared baking dish. Spread it out evenly with a spoon. It should look moist and ready for the final cheesy touch.

Sprinkle the shredded cheddar cheese generously over the top of the pasta. Make sure to cover the edges. The cheese will melt into a beautiful golden crust in the oven.

Place the dish in the oven and bake for 20 to 30 minutes. The cheese should be melted and the sauce should bubble. If you like it crispy, broil for two minutes.

Remove the dish from the oven carefully. Let it sit for five minutes to allow the sauce to set. Sprinkle fresh parsley over the top and serve it while it is hot.