Chicken Cordon Bleu Casserole

From Tasty Kitchen

1 whole cooked chicken (rotisserie works great) deboned and shredded (about 5-6 cups)
1/2 lb very thinly sliced deli-style honey ham, rough chopped
1/4 lb thinly sliced baby swiss cheese

Sauce:
4 T butter
4 T flour
3 cups milk
2 T fresh squeezed lemon juice
1 T dijon mustard
1 1/2  t salt
1/2 t smoked paprika
1/4 t white pepper

Topping:
6 T butter
1 1/2 c Panko bread crumbs
3/4 t seasoning salt
1 1/2 t crushed dried parsley

Preheat oven to 350. Butter a 9x13 dish, set aside
Put cooked, shredded chicken on bottom of baking dish, cover with rough chopped ham, cover with sliced swiss cheese.
For sauce: Melt butter over medium heat, mix with flour to form a roux. Slowly add milk while stirring until sauce thickens. Stir in lemon juice, mustard, salt, paprika, and pepper. Bring to soft boil and turn off heat. Pour sauce evenly over the casserole, making sure to get edges.
For topping: melt butter, add remaining ingredients, then sprinkle over the top of the casserole.
Bake uncovered for 45 minutes until hot throughout and a light golden brown. Remove from oven and let cool 5-10 minutes prior to serving.