Chicken cordon bleu lasagna is everything you want the classic dish to be, but it's all taken up a notch. The chicken will never dry out because it's smothered in a delicious bechamel sauce, and the bacon and ham play nicely off each other. The lasagna noodles make it even heartier, and because the bechamel is made entirely with Swiss cheese, that dominant flavor is woven throughout.
The best thing about this dish however, might be that it's a great way to use up leftovers! With the ham and chicken already cooked, this dish will come together in just a few minutes, but it's so decadent those you serve it to will think you've spent the entire day in front of the stove.
Preheat oven to 350 degrees Fahrenheit (180 degrees Celsius).
Place the butter in a medium-sized saucepan set over medium heat. Once it melts, add the all-purpose flour and whisk to combine completely. Let cook for 2 minutes so the raw flour can cook out. Slowly add the milk, whisking as you do to break up the clumps. Add the pinch of nutmeg and turn heat off under pan. Slowly stir in the Swiss cheese in parts, waiting until one addition is completely melted before adding the next. Season lightly with salt and white pepper.
Spoon about ½ cup of the bechamel sauce into the bottom of a 9" x 13" casserole dish. Layer on lasagna noodles, then cooked chicken, then bacon, then ham. Spoon some more bechamel over top, then repeat layers until all noodles, chicken, ham and sauce are used. End with lasagna noodles and the bechamel poured over top. Sprinkle generously with mozzarella cheese.
Place lasagna in the oven, uncovered, and bake for 45 to 60 minutes until the top is golden brown and the entire thing is hot and bubbling throughout. Remove from oven and let rest for 5 minutes before slicing into it.