Preheat the oven to 180°C (350°F).
Cook the spaghetti according to package instructions until al dente.
Drain the pasta and set aside.
In a large bowl, combine shredded chicken and the entire undrained can of Rotel tomatoes and chilies.
Add the cream soup and mix well.
Stir in ½ cup milk or chicken broth until the sauce becomes smooth and creamy.
Stir in garlic powder, salt, and pepper.
Add 1 cup shredded cheddar cheese.
Fold in the cooked spaghetti until evenly coated.
Transfer the mixture to a greased baking dish.
Sprinkle the remaining cheese on top.
Bake for 20–25 minutes if warm, or 30–35 minutes if refrigerated before baking
Let it rest for 5 minutes before serving.