Boil 12 lasagna noodles according to the package instructions. Drain the noodles in cold water and set them aside. Heat the oven to 375 degrees Fahrenheit and spray a 13 x 9 x 2-inch baking dish with non-stick cooking spray.
In a large skillet, melt ¼ cup unsalted butter over medium heat. Once melted, add 2 teaspoons minced garlic and cook for 30 seconds until fragrant. Sprinkle in ¼ cup all-purpose flour and stir to make a paste.
Whisk in 1 cup chicken broth, 2½ cups heavy cream, and 1 cup grated parmesan cheese.
Stir in 1 (8-ounce) jar sun-dried tomatoes, 2 teaspoons paprika, and 1 tablespoon dried Italian seasoning. Season with salt and pepper to taste. Simmer the sauce over medium-low heat for 3-5 minutes or until the sauce thickens.
Add 3 cups cooked and shredded chicken and 2 cups chopped spinach.
Stir to combine until the spinach starts to wilt. Set the finished sauce aside until assembly.
Ricotta Layer
In a large bowl, add 1 (15-ounce) container ricotta cheese, 1 cup grated parmesan cheese, 1 large egg, 1 teaspoon salt, and ½ teaspoon black pepper. Stir until smooth and combined.
To Assemble
To assemble the lasagna, start by spreading ½ cup of the meat sauce on the bottom of the baking dish. Arrange the noodles in a single layer over the meat sauce.
Spread ½ cup of the ricotta mixture on top of the noodles.
Add ¾ cup of the meat sauce on top of the ricotta layer followed with ½ cup of the 2½ cups shredded mozzarella cheese.
Repeat the layers two more times. Finish off the top with a final layer of noodles, the remaining meat sauce, and the remaining 1 cup of mozzarella cheese. Cover with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 10 minutes, or until bubbly.
Notes
Store and Reheat: Store cooled lasagna in an airtight container and keep in the fridge for 3–5 days or freeze for up to 1 month. Reheat individual portions in the microwave for 1–2 minutes.