01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or nonstick spray.
02 - If using regular lasagna noodles, cook them according to package directions until al dente. Drain and lay flat on a clean surface to prevent sticking.
03 - In a medium saucepan over medium heat, melt the butter. Whisk in the flour and cook for 1 to 2 minutes, stirring constantly to form a smooth roux.
04 - Gradually whisk in the milk, stirring constantly to prevent lumps. Continue cooking until the sauce thickens, about 5 minutes.
05 - Stir in the Dijon mustard, garlic powder, onion powder, salt, and black pepper until well incorporated. Remove from heat.
06 - Spread a thin layer of béchamel sauce across the bottom of the prepared baking dish. Arrange a layer of noodles over the sauce.
07 - Top the noodles with half of the chicken, half of the ham, and one-third of the Swiss cheese. Spoon additional sauce evenly over the layer.
08 - Add another layer of noodles, followed by the remaining chicken, remaining ham, another third of the Swiss cheese, and more sauce.
09 - Finish with a final layer of noodles. Pour the remaining sauce over the top and sprinkle evenly with mozzarella and Parmesan cheese.
10 - Cover the dish tightly with aluminum foil and bake for 30 minutes.
11 - Remove the foil and continue baking for 15 to 20 minutes until the cheese is golden and bubbly.
12 - Let the lasagna rest for 10 minutes before slicing to allow the layers to set. Garnish with fresh chopped parsley if desired.