01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish and set aside.
02 - If using regular lasagna noodles, cook them according to package directions until al dente. Drain and set aside. No-boil noodles can be used directly from the package.
03 - In a medium saucepan over medium heat, melt the butter. Whisk in the flour and cook for 1 to 2 minutes to form a roux.
04 - Gradually whisk in the whole milk, stirring constantly to prevent lumps. Continue cooking until the sauce thickens, approximately 5 minutes.
05 - Stir in the Dijon mustard, garlic powder, onion powder, salt, and black pepper until well combined. Remove from heat.
06 - Spread a thin layer of béchamel sauce evenly across the bottom of the prepared baking dish.
07 - Arrange a layer of noodles over the sauce. Top with half of the shredded chicken, half of the sliced ham, and one-third of the Swiss cheese. Spoon additional béchamel sauce over the layer.
08 - Repeat the layering with noodles, the remaining chicken, the remaining ham, another third of the Swiss cheese, and more sauce.
09 - Finish with a final layer of noodles, the remaining béchamel sauce, the mozzarella cheese, and the Parmesan cheese.
10 - Cover the baking dish tightly with aluminum foil and bake for 30 minutes.
11 - Remove the foil and continue baking for an additional 15 to 20 minutes, until the top is golden brown and the edges are bubbly.
12 - Let the lasagna rest for 10 minutes before slicing to allow the layers to set. Garnish with chopped fresh parsley if desired.