In a medium saucepan over medium heat, melt the butter.
Add the minced onion and minced garlic.
Sprinkle in the flour and stir to combine.
Whisk chicken broth and milk into flour mixture. Stir constantly until sauce thickens, about 2 minutes. Remove from heat and stir in Italian seasoning, salt, and pepper.
Cook chicken and mushrooms until the chicken is cooked through, about 5 minutes.
Then add in the spinach leaves, stirring gently until just wilted. Remove from the heat.
Spread half of the sauce on the bottom of the baking dish sprayed with non-stick spray.
Lay 3 lasagna noodles halves on the sauce.
Add half of the chicken, mushroom, and spinach mixture.
Add all of the cottage cheese or ricotta cheese then spread flat if using cottage cheese.
Sprinkle with half of the mozzarella and half of the Parmesan cheese.
Repeat the layers except for the cottage or ricotta cheese.
Cover with aluminum foil and bake 35 minutes on middle rack with a baking sheet under it on lower rack.
Uncover and bake another 10 minutes until hot and bubbly.