Cook the spaghetti in a large pot of boiling salted water until al dente, following package instructions. Drain and set aside.
In a skillet, heat a small amount of oil over medium heat. Add the cooked, shredded chicken and cook until slightly browned and heated through, about 5 minutes. Remove from heat.
In a large mixing bowl, combine the cooked spaghetti, shredded chicken, Rotel tomatoes, cream of mushroom soup, garlic powder, salt, and pepper. Mix until well incorporated, resulting in a chunky, creamy mixture.
Pour the mixture into a greased baking dish, spreading it evenly. Sprinkle the shredded cheddar cheese over the top.
Bake in a preheated oven at 375°F (190°C) for approximately 25-30 minutes, or until the cheese is melted and bubbly with golden edges. Listen for a bubbling sound indicating it’s ready.
Remove from oven and let rest for 5 minutes before serving. Optionally, garnish with additional shredded cheese or chopped herbs.
