Bring a large pot of salted water to a boil. Add the spaghetti and cook until al dente, about 8-10 minutes. Drain and set aside.

In a large skillet, cook the diced bacon over medium heat until crispy, about 6-8 minutes. Remove bacon, leaving the fat in the skillet.

Sauté the chopped onion in the bacon drippings for 3-4 minutes, then add minced garlic for another minute.

Melt 2 tablespoons of butter into the skillet, then add cream cheese and chicken broth, whisk until smooth and creamy.

Fold in the undrained can of Rotel tomatoes and simmer for about 5 minutes.

Stir in shredded chicken and drained spaghetti, mixing well to coat with sauce. Heat through for about 3 minutes.

Mix in 1 cup of Monterey Jack cheese until melted and well incorporated.

Preheat the oven to 350°F (175°C). Transfer mixture to a greased 9x13 baking dish, top with remaining cheese and bacon.

Bake for 20 minutes until edges are bubbling and cheese is golden, then let sit before serving.