Prepare two 9x13 casserole dishes spraying lightly cooking spray. Set aside.

Heat a dutch oven or stockpot over medium-high heat. Coat the skillet with olive oil.

Add the onion, garlic, 1 1/2 teaspoon salt, thyme, red pepper, and mushrooms. Cook for about 8 minutes and then stir in the spinach a handful at a time to allow the spinach to cook down. Stir in the chicken, remove from heat, and set aside.

In a large saucepan, combine the milk, 1 1/2 teaspoons of remaining salt, and nutmeg, broth, and bring to a slow simmer over medium heat. When bubbles begin to form, gradually whisk in flour and let simmer until thick stirring often. About 5-10 minutes.

Remove the saucepan from the heat and stir in the Italian cheese blend. 

Pour ¾ cup of the sauce into the bottom of each casserole dish. Top the sauce in each dish with a layer of noodles. Do not overlap the noodles. Next, add a layer of the chicken mixture and a sprinkle of mozzarella cheese. Repeat the layering, finishing with a layer of sauce. Top with any remaining mozzarella cheese.

Cover each dish with aluminum foil and refrigerate overnight.

To bake, remove the lasagna from the refrigerator about 20 minutes before baking. Preheat the oven to 375 degrees. Bake, covered, for 25 minutes. Uncover the casserole dishes and continue to bake for 10 to 15 minutes or until lightly browned and bubbly around the edges.

How to freeze:  Cover tightly with aluminum foil and freeze for up to 2 months. Thaw in the refrigerator overnight. Follow the above instructions to bake.