Cook the lasagna noodles in a large pot of boiling salted water according to package instructions, usually about 8-10 minutes. Drain and set aside.
In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add minced garlic and sauté for about 30 seconds until fragrant.
Add the sliced mushrooms, zucchini, and diced red bell pepper to the skillet. Sauté for about 5 minutes, shifting the veggies until slightly tender.
Stir in the fresh spinach and cook until wilted. Season with oregano, basil, red pepper flakes, salt, and pepper. Remove from heat.
In a separate bowl, combine ricotta cheese, half of the mozzarella, and half of the Parmesan cheese. Mix well and set aside.
In a 9x13 inch baking dish, spread 1 cup of alfredo sauce on the bottom.
Layer 3 lasagna noodles over the sauce. Spread half of the ricotta mixture over the noodles, followed by half of the sautéed vegetable mixture. Pour 1 cup of alfredo sauce over the veggies.
Repeat the layers: add 3 lasagna noodles, the remaining ricotta mixture, the remaining sautéed vegetables, and another cup of alfredo sauce.
Top with the last 3 noodles, remaining alfredo sauce, and sprinkle the remaining mozzarella and Parmesan cheese on top.
Cover the dish with foil (to prevent sticking) and bake for 25 minutes. Remove the foil and bake for another 15-20 minutes, until the cheese is bubbly and golden brown.
Let it cool for 10 minutes before slicing and serving.
Notes
Feel free to add or substitute any vegetables you like.