Cook the lasagna noodles according to the instructions on the package. Drain and leave them soaking in cold water to avoid sticking. Drain right before using.

Season both sides of the chicken breasts with salt and pepper. Heat 2 tbsp of oil in a large pan over medium high heat and cook the chicken for 5-7 minutes. Lower the heat to medium, flip the chicken over and cook for another 5-7 minutes or until it is no longer pink. Remove from the pan, let it cool and chop it into small pieces.

Clean the mushrooms well and cut them into thin slices. Heat 1 tbsp of oil over medium heat in the same pan that was used to cook the chicken. Add the white onion and cook for 3-5 minutes or until it is translucent. Add the garlic and cook for another minute. Now add the sliced mushrooms, season with salt and pepper and cook until they are soft, about 5-8 minutes. Add heavy cream, stir well and cook for another two minutes. Check for seasoning, remove from the heat and set aside.

SAUCE: Melt the stick of butter in a medium saucepan over medium low heat. Add the flour and mix well until it turns into a golden yellow color, this can take between 7-8 minutes. Slowly add the cold milk while constantly whisking. (I have always made it with cold milk and never stop whisking with wonderful results). Keep whisking until it is smooth. Bring it to a boil and cook for about 10 minutes. Remove from the heat and season with the nutmeg and salt and pepper to taste. Set aside.

Pre-heat oven at 375ºF (190ºC).

ASSEMBLE: Cover the bottom of the baking pan with cooking spray or a little bit of oil. Spread about 2-3 tbsp of white sauce on the bottom. Top sauce with 3-5 lasagna noodles (depending on the size of your baking pan). Spread 1/3 of white sauce over the noodles. Add ½ amount of chopped chicken. Add ½ the amount of cooked mushrooms. Sprinkle 1/3 the amount of mozzarella cheese. Repeat with a layer or noodles, white sauce, chicken, mushrooms and 1/3 mozzarella cheese. Finish with a layer of noodles, white sauce, the last 1/3 of mozzarella and the Parmesan cheese.

Cover the lasagna with nonstick aluminum foil or spray regular aluminum foil with cooking spray. Place it on a cooking sheet and bake it for 20-25 minutes. Remove the aluminum foil and bake for another 15-20 minutes or until the cheese melts on top. Let it set for about 15-20 minutes before serving.