Boil the lasagna noodles in salted water until just tender. Drain and lay them flat so they don’t stick together. I always drizzle a little oil to keep them smooth.
Melt butter in a saucepan, then whisk in flour until smooth. Slowly add milk while stirring continuously to avoid lumps. Cook until thick and creamy, then season with garlic, salt, and pepper.
In a bowl, mix shredded chicken, ricotta cheese, spinach, and seasoning. I like to keep it well combined so every bite is flavorful. This layer gives the lasagna its hearty texture.
Start with a thin layer of sauce at the bottom of the dish. Add noodles, then chicken mixture, sauce, and cheese. Repeat the layers until everything is used, finishing with cheese on top.
Cover with foil and bake in a preheated oven at 180°C (350°F) for about 25 minutes. Remove foil and bake another 10–15 minutes until the top is golden and bubbly.
Let the lasagna rest for 10–15 minutes before slicing. This helps the layers set properly. I always find it easier to cut and serve after resting.