Instructions:

Preheat oven to 375°. Spray a shallow 2-quart oven-proof casserole dish with cooking spray. Following package directions, bring a large pot of water to a boil. Add pasta; cook per package directions, until pasta is al dente. Drain well and set aside.

Meanwhile melt butter over medium-low heat in a medium saucepan; stir in flour, salt, pepper and nutmeg. Stirring constantly, bring to a low simmer; cook 1 minute. Gradually whisk in milk and bring to a boil while continuously stirring. Reduce heat, and simmer for 1 minute. Remove from heat; stir in onion and lemon juice. Add cheddar cheese, Swiss cheese and ham; stir until cheese is just melted. Stir in hot pasta. Pour into dish.

To prepare crumb topping, melt butter in a small saucepan over medium-low heat. Add shallots; stirring, cook until just softened, about 1 minute. Remove from heat; stir in panko, Swiss cheese and parsley. Sprinkle over top of casserole.

Bake for 20-25 minutes or until bubbly and crumbs are golden brown.