Preheat oven to 375 degrees F. Grease a 9x13-inch baking dish. Set aside.
Heat olive oil (or butter) in a large 12-inch skillet, over medium-high heat. Add the chicken pieces. Season chicken with the Italian seasoning, minced garlic, seasoned salt and pepper. Stir and cook for 5 minutes.
Add the broccoli florets to skillet. Continue to stir until chicken is no longer pink in the center. Turn the heat off.
Meanwhile, boil the egg noodles in water until al dente. Drain water and then cover. Set aside.
Add cream of chicken soups, sour cream, milk, and 1/2 cup of sharp white cheddar and 1/2 cup of mild cheddar to the chicken and broccoli skillet. Next, add the cooked noodles. Carefully mix everything together.
Pour mixture into the prepared baking dish. Spread out evenly. Sprinkle the remaining cheeses all over the top. Cover with foil and bake for 20 minutes.
Carefully remove baking dish from oven. Remove foil and sprinkle fried onions all over the top. Place dish back in oven, uncovered, for 5 more minutes. Remove from oven and let stand about 5 minutes to cool slightly. Serve and enjoy!