Preheat your oven to 375°F (190°C).
In a large skillet, heat olive oil over medium heat.
Add minced garlic to the skillet and sauté for about 1 minute until fragrant.
Incorporate the sliced mushrooms and cook until softened, about 5 minutes.
Add the chopped spinach and cook until wilted, about 2-3 minutes.
Season the mixture with salt, pepper, and oregano, then remove from heat.
In a mixing bowl, combine the shredded chicken and ricotta cheese.
Spread a thin layer of the mushroom and spinach mixture on the bottom of a baking dish.
Layer three lasagna noodles over the vegetable mixture, then spread half of the chicken-ricotta mixture on top.
Add another layer of the mushroom and spinach mixture followed by another layer of noodles.
Repeat layers with remaining chicken-ricotta mixture, noodles, and finish with a final layer of mushrooms and spinach, topped with mozzarella and Parmesan.
Cover the dish with aluminum foil and bake for 25 minutes.
Remove foil and bake for an additional 15 minutes until the top is golden and bubbly.
Let the lasagna cool for 10 minutes before serving.