Melt butter in a medium saucepan over medium heat. Whisk in flour and cook for 2 minutes. Gradually add heavy cream, whisking to eliminate lumps. Stir in garlic, Italian seasoning, chicken base, and onion powder. Simmer for 5 minutes, then mix in Parmesan cheese until melted.

Bring a large pot of salted water to a boil. Cook lasagna noodles for 8-10 minutes. Drain and rinse under cold water, laying them flat to prevent sticking.

In a bowl, combine ricotta cheese and spinach. Season with salt and pepper until well combined.

Preheat oven to 350°F (175°C). Spread a layer of Alfredo sauce in a baking dish. Layer noodles, chicken, ricotta mixture, and mozzarella. Repeat twice, finishing with Alfredo.

Cover with foil and bake for 30 minutes. Remove foil and bake another 15-20 minutes until golden.

Let the lasagna rest for 30-60 minutes before serving.