Put chicken in large pot with 4-5 cups of water. Simmer chicken on medium heat until no longer pink-cube chicken in pan. Mix in the 3 packets of seasoning from the noodle package. Add noodles, and continue to simmer until the noodles are soft.
Reduce heat to low-stir in the sour cream and garlic powder to taste. Combine the half & half with the corn starch (mix well) then add to the pot and stir well. Let simmer again for about 5 min on low to let the sauce thicken up.