Cook the spaghetti according to the package instructions. Drain and set aside.

Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking dish with butter.

Make the sauce: In a large saucepan over medium heat, combine Velveeta, milk, cream of chicken soup, Rotel, garlic powder, and onion powder. Stir until the cheese is fully melted.

Mix everything together: Add the cooked spaghetti and chicken to the cheese sauce, stirring well to coat everything evenly.

Assemble the casserole: Pour the mixture into the prepared baking dish and spread evenly. Sprinkle shredded cheddar cheese on top.

Bake for 20-25 minutes, or until bubbly and the cheese is melted.

Serve hot and enjoy this creamy, cheesy comfort dish!