Chicken Cordon Bleu Casserole

For the topping, add melted butter to bread crumbs and mix. Set aside. For the filling, preheat the oven to 400 degrees, making sure the oven rack is in the middle. Place the potatoes, 6 cups of water and 1 teaspoon of salt in a large pot. Bring to a boil over high heat, then reduce heat to a simmer and cook, uncovered, until the potatoes are partially cooked, about 2 minutes. (Don't overcook because the potatoes will continue to cook in the oven.) Drain the potatoes and set aside. In the same pot you used to cook the potatoes, melt the butter over medium heat. Add the onion, thyme, and 1/2 teaspoon salt. Cook until the onions are softened, about 6 minutes. Add the garlic and cook until fragrant, about 1 minute. Add the flour and cook, stirring constantly, until golden, about 1 minute. Slowly whisk in the chicken broth and the milk. Bring the mixture to a simmer, whisking often, until slightly thickened. Remove from heat and stir in the swiss cheese, ham and chicken. Add the drained potatoes and mix well. Pour mixture into a 9 x 13 inch baking pan. Sprinkle with bread crumb topping. Bake until the chicken is cooked through and the casserole is bubbling, about 30 to 35 minutes. Cool 10 minutes before serving.