• Preheat oven to 375 degrees Fahrenheit.
• Butter or oil a 9x13 inch baking dish.

Make Chicken

• Place chicken breasts or chicken thighs in a medium-large saucepan and cover with water.
• Bring to boil on medium heat. After boiling, reduce heat to medium-low and cover the pot with a lid.
• Boil the chicken, depending on its size, for between 15 and 25 minutes. A meat thermometer can be used to check the temperature. It should be inserted into the thickest portion of the meat and read 165 degrees Fahrenheit.
• Transfer the chicken to a large bowl. Then, use two forks to shred it.

Cook Spaghetti:

• Add the spaghetti to a large pot. If necessary, break them in half. Stir in a little oil. Follow the package instructions and cook for about 2 minutes.
• After the pasta has been cooked, you should reserve 2 cups of the cooking liquid. Discard any excess. Drain the pasta.

Assemble:

• Add cooked spaghetti, condensed milk of mushroom soup, grated cheese and diced onion to the large bowl. Mix well.
• Add 1 cup broth or other reserved cooking liquid to the mixture and adjust for salt. Add 1 cup of broth or reserved cooking liquid to the mixture and stir well.
• Place the mixture in a baking dish and evenly distribute it.
• Buttery Cracker Topping
• Combine cracker crumbs and melted butter in a large bowl until well combined.
• Place the crumb mixture over the casserole. Sprinkle the remaining 1 1/2 cups cheese on top. Spread evenly.
• Add the rest of the bacon.

Baking:

• Bake for between 30-40 minutes, or until cheese is melted and mixture is bubbly.