Preheat oven to 350℉. Grease a 13x9 inch casserole dish. Set aside.
Bring a large pot of water to a boil over high heat. Once the water boils, stir in the chicken bouillon.
Once the chicken bouillon is dissolved, add the chicken breasts and boil for 20 minutes.
Remove chicken breasts from the pot with tongs and transfer them to a cutting board. Keep the water boiling.
Add broken spaghetti noodles to the pot of boiling water that the chicken cooked in and cook the pasta noodles according to package directions till al dente.
While the pasta is cooking, use two forks to shred the chicken breasts. Set aside.
Melt butter over medium heat in an extra large skillet.
Add the chopped onion and sauté until it's soft and translucent, about 5 minutes.
Add Creole seasoning, garlic powder, onion powder, salt, and pepper to the onions in the pan.
Stir to combine and "bloom" the spices.
Add the minced garlic to the pan and cook until fragrant, about 30 seconds.
Pour in heavy cream and stir to combine.
Add the two cans of cream of chicken soup, and the can of cheddar cheese soup. Stir to combine.
Add about ½ of the shredded cheddar cheese to the sauce.
Bring to a low simmer and stir until you have a thick smooth sauce, about 3-4 minutes.
Add 3-4 ladles (about 1 to 1½ cups) of the pasta water that the spaghetti is cooking in to thin out the sauce.
Add the frozen vegetables to the sauce and cook until heated through, about 3-4 minutes. Remove from heat.
When pasta is cooked, drain and add the spaghetti to the sauce in the pan.
Add the shredded chicken to the pan and stir until the pasta and the shredded chicken are coated in the sauce.
Transfer the mixture to a greased 13x9 inch oven safe casserole dish.
Top with the remaining cheddar cheese, and the shredded mozzarella cheese.
Sprinkle with an even layer of French fried onions.
Cover the casserole dish with foil and bake at 350℉ for 30 minutes.
Remove foil and bake for an additional 25-30 minutes or until hot and bubbly.
Remove from the oven and allow to rest for 15 minutes before serving. Sauce will thicken as it cools.
Serve with garlic bread and a crisp green salad to round out the meal.