Preheat oven to 375° F. Cook egg noodles, drain, and leave in colander for now. In a small saucepan, mix soup and milk together and cook on low (do not let it boil!!), when warm, add cheese until cheese melted. Mix chicken/tuna and mayo in a bowl, adding enough onion powder to taste (actually want it to be a little strong taste to be perfect for the entire casserole). Mix together tuna mixture with melted cheese mixture, mix well. Add noodles, mixing really well. Place in a sprayed casserole dish and bake for 25-30 minutes. The entire process takes about an hour from start to finish, served with a salad, quick, easy meal while you are sewing!!