Heat a large skillet to medium-high and add 2 tablespoons of butter along with 2 minced garlic cloves and 1 cup of chopped onion. Cook the onion until it becomes translucent.
Now add 10 ounces of fresh spinach and stir until the spinach wilts.
Then add in 4 cups of heavy cream, 1 ½ cup of grated Parmesan, 15 ounces ricotta cheese, ¼ teaspoons black pepper, 1 ½ teaspoons salt, and 3 cups of shredded rotisserie chicken.
Once the heavy cream comes to a slight simmer, remove it from the heat.
In a 9 x 13 inch deep baking dish add a large spoonful of the chicken Alfredo mixture to coat the bottom of the pan then begin adding in your cooked lasagna noodles. I was able to squeeze in about 5 noodles.
Now add a generous amount of your chicken Alfredo mixture on top of the lasagna noodles and sprinkle on one-third of the shredded mozzarella cheese.
Repeat layering the lasagna noodles, chicken Alfredo, and shredded mozzarella until all 15 of your lasagna noodles are assembled. Now cover the lasagna with foil and bake at 350 degrees Fahrenheit for 35-35 minutes. Then broil uncovered for 2-3 minutes to brown the cheese.