Boil the spaghetti in salted water until al dente, about 8–10 minutes. Drain and set aside.

Cook the diced bacon in a skillet over medium heat until crispy, about 5–7 minutes. Remove and reserve the drippings.

Sauté the chopped onion and minced garlic in the bacon drippings for 3–4 minutes until translucent.

Add butter, cream cheese, and chicken broth to the skillet. Stir until smooth and creamy, about 3–5 minutes.

Fold in the Rotel tomatoes and simmer for 2–3 minutes.

Stir in the shredded cooked chicken, then add the drained spaghetti, mixing until well coated.

Sprinkle in half the Monterey Jack cheese, stirring until melted and combined.

Transfer to a greased baking dish, top with remaining cheese and bacon, and bake at 350°F for about 20 minutes.

Bake until cheese is bubbly and edges are golden brown.