Prepare pasta according to package directions; rinse and set aside.
In Dutch oven, sauté onion and garlic in butter for about 2 minutes. Add both cans of soup, A.1 Original Sauce, milk, Cajun spice and 1 1/2 cups of the cheese. Stir until melted and smooth. Add spaghetti noodles and chicken. Mix well. Stir in peas.
Spread ingredients in 9 x 13 baking pan and cover with foil. Bake at 350 degrees for 30 minutes. Remove foil.
Sprinkle remaining cheese, roasted red pepper chunks, and parsley over the top. Bake 5 minutes or until cheese is melted.