Preheat your oven to 375°F (190°C).
Boil a large pot of salted water. Add the gluten-free lasagna noodles and cook according to package instructions until al dente. Drain and set aside.
In a skillet, heat olive oil over medium heat. Add diced onion and sauté until translucent, about 5 minutes.
Stir in minced garlic and cook for another minute until fragrant.
Add shredded chicken and fresh spinach to the skillet, cooking until the spinach wilts, about 2-3 minutes. Season with salt, pepper, and Italian herbs. Remove from heat.
In a mixing bowl, combine the ricotta cheese with half of the mozzarella cheese and half of the parmesan cheese. Mix well until incorporated.
Spread a thin layer of marinara sauce at the bottom of the baking dish. Layer 3 lasagna noodles over the sauce.
Spread half of the ricotta mixture over the noodles, followed by half of the chicken and spinach mixture. Add another layer of marinara sauce, then repeat the layers (noodles, ricotta, chicken mixture, marinara).
For the final layer, place the last 3 lasagna noodles on top, spread the remaining marinara sauce evenly, and top with the remaining mozzarella and parmesan cheese.
Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Allow the lasagna to cool for 10 minutes before slicing. Serve warm.