Preheat your oven to 350°F (175°C).
Cook the gluten-free lasagna noodles according to package instructions, then drain and set aside.
In a large skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute until fragrant.
Add the shredded chicken, spinach, oregano, salt, and pepper to the skillet. Cook for an additional 3-5 minutes, stirring until the spinach is wilted. Remove from heat.
In a mixing bowl, combine the ricotta cheese, half of the mozzarella cheese, and half of the Parmesan cheese. Mix well.
Spread a thin layer of marinara sauce on the bottom of a 9x13 inch baking dish.
Layer 4 lasagna noodles over the sauce, followed by half of the chicken mixture, half of the ricotta mixture, and one-third of the remaining marinara sauce. Repeat the layers with 4 more noodles, the remaining chicken mixture, and another layer of the ricotta mixture. Top with the final 4 noodles and the last of the marinara sauce.
Sprinkle the remaining mozzarella and Parmesan cheese evenly over the top.
Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden.
Let the lasagna rest for 10 minutes before slicing. Garnish with fresh basil leaves, if desired.