Chicken Codon Bleu

Layer in large greased casserole dish:
3 c. penne noodles, cooked
4 c. chicken, cooked nad diced
1/2 lb. thinly sliced deli ham, chopped
1/4 lb. thinly sliced baby Swiss cheese
Sauce:
In saucepan:
4 tbsp. butter
4 tbsp. flour
Mix until bubbly, slowly stir in 3 c. whole milk, stirring until thickens, may need a little more if it is too thick.
Add:
2 tbsp. lemon juice
1 tbsp dijon mustard, I like to add a little more
1/2 teas. salt
1/2 teas. smoked paprika
1/4 teas. white pepper
Pour over Mixture.
Topping:
1 1/2 c. ritz crackers
4 tbsp butter
1 1/2 teas. parsley
Bake 350 degrees 45 minutes or until hot and bubbly and topping is golden brown