Creating the Monterey Chicken Spaghetti Casserole is simple and fun if you follow these easy steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Sauté Vegetables: In a skillet, heat the olive oil over medium heat. Add the diced bell pepper and onion. Sauté until they are soft, about 5-7 minutes.
3. Combine Chicken and Spaghetti: In a large mixing bowl, combine the cooked spaghetti, shredded chicken, sautéed vegetables, cream of mushroom soup, and sour cream. Mix well.
4. Season: Add garlic powder, onion powder, salt, and pepper. Stir until everything is evenly coated.
5. Layer Ingredients: In a greased 9×13-inch baking dish, spread half of the spaghetti mixture. Sprinkle half of the Monterey Jack and cheddar cheese on top.
6. Add Remaining Mixture: Spread the remaining spaghetti mixture on top, then top it off with the rest of the cheese.
7. Bake: Cover with aluminum foil and bake for 20 minutes. Then remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and golden.
8. Cool and Serve: Allow the casserole to cool for about 5 minutes before slicing and serving.

By following these simple steps, you’ll be on your way to serving a delicious and hearty Monterey Chicken Spaghetti Casserole that your family will love.