Preheat & Prep – Set oven to 350°F and grease a 9×13-inch baking dish.
Sauté the Veggies – Heat olive oil in a skillet over medium heat. Cook onions and garlic until soft. Add mushrooms and sauté until tender. Season with salt and pepper.
Prepare the Chicken Sauce – In a bowl, combine Alfredo sauce with cooked chicken.
Mix the Ricotta Blend – In another bowl, mix ricotta, egg, ½ cup Parmesan, and Italian seasoning.
Start Layering – Spread a thin layer of chicken Alfredo sauce in the baking dish. Add three lasagna noodles.
Add Fillings – Spread half of the ricotta mixture, then half of the mushrooms, followed by a third of the mozzarella.
Repeat Layers – Add another set of noodles, remaining ricotta mixture, mushrooms, and another third of mozzarella.
Final Touches – Top with last layer of noodles, remaining Alfredo sauce, mozzarella, and Parmesan.
Bake to Perfection – Cover with foil and bake for 40 minutes. Remove foil and bake for another 20 minutes until cheese is bubbly and golden.
Rest & Serve – Let lasagna sit for 10 minutes before slicing. Garnish with parsley and serve hot.