Pre-heat the oven to 350. Lightly mist a 9x13 baking dish with cooking spray and set aside.

Cook pasta in salted water according to package instructions. Drain and set aside.

While the water is boiling for step one, melt 3 tablespoons of the light butter in a medium saucepan over medium-low heat. Add the flour to the butter and stir to combine. Add the milk a little at a time and whisk the flour mixture into the milk until smooth. Add the salt and pepper and stir to combine. Turn the heat up to medium and add the swiss cheese to the milk mixture. Whisk together for about 5 minutes until smooth and thick.

Combine the cooked pasta, chicken, ham, sour cream and cheese sauce and stir until well mixed. Spread the mixture evenly into the prepared baking dish.

Place the remaining tablespoon of light butter in a skillet over medium heat until melted. Add the bread crumbs and Parmesan and brown breadcrumbs for 1-2 minutes, stirring frequently. Sprinkle the bread crumb/Parmesan mixture over the top of the casserole and bake for about 30 minutes until golden and bubbly.