Start by cooking your pasta according to box instructions, but draining a bit before al dente. The pasta will continue to cook in the oven and we want it to soak up all the juices. Return the cooked spaghetti to the pot.
While the water is boiling for the pasta, pre-heat the oven to 350F. Dice chicken breasts into 1/2 inch cubes. Add the olive oil and butter to a large 12 inch skillet and melt. Add the diced chicken and seasoning to the skillet. Cook the chicken about 7 minutes until cooked through. Remove the chicken and set aside, leaving behind the liquid.
Add the onion and pepper to the skillet and saute for about 5 minutes. Add the garlic and saute for 30 seconds to 1 minute. Dust the skillet with flour and mix to cook out the raw flour until mixture is thickened.
Slowly add 1/2 cup at a time of chicken stock to form the roux, stirring between pours and waiting for the roux to thicken each time. After all the chicken stock has been incorporated, add the can of Rotel and room temperature cream cheese. Mix until cream cheese has fully melted.
In the still warm pasta pot, combine the pasta, chicken, and sauce. Stir well and transfer to a casserole dish. Top with shredded cheeses and bake for 15 minutes until cheese is melted but not browned.
Top with optional fresh parsley and parmesan cheese for garnish.
Store leftovers in an air tight container kept in the refrigerator for 3-4 days.
You may use freshly shredded cheese or opt for bagged pre-shredded cheese.