Place a saucepan over medium heat. Add the butter and when it’s melted and no longer foaming, stir in the garlic and flour. Cook 30 seconds, then gradually whisk the milk into the pan. Bring to a simmer and cook until the sauce is thickened. Remove from the heat and add the Parmesan, cream cheese and spinach. Stir until the spinach is wilted.
assemble the lasagna
Whisk the egg and ricotta in a small bowl until blended.
Spoon about 1/4 cup sauce on the baking dish and top with 2 lasagna noodles, followed by ¼ cup of the ricotta, 2/3 cup chicken, 2/3 cup mozzarella, 1 tablespoon Parmesan and ½ cup of the sauce. Repeat the layers twice more and pour the remaining sauce and Parmesan over the top layer of noodles.
Bake uncovered 20-25 minutes, until the sauce is bubbling.
Let the lasagna cool for 15-20 minutes before serving.
Leftover or rotisserie chicken work great for this recipe!