Avocado Chicken Casserole

1/4 c. butter or margarine
1/4 c. all-purpose flour
1/2 tsp. salt
1/4 tsp. each: garlic powder, onion powder, dried basil, marjoram and thyme
1 1/2 c. milk
1 c. half-and-half cream
8 oz. med. egg noodles (cooked and drained)
3 med. ripe avocados (peeled and sliced)
3 c. cubed cooked chicken
2 c. shredded cheddar cheese

In a large saucepan, melt butter. Stir in flour and seasonings until smooth. Gradually add milk and cream. Bring to a boil, cook and stir for 2 minutes. Remove from the heat. In a greased 13 X 9 X 2-inch baking dish, layer half of the noodles, avocados, chicken, white sauce and cheese. Repeat layers. Cover and bake at 350 for 20 to 25 minutes. Uncover, bake 5 minutes longer or until bubbly.