Preheat oven to 375°F and grease a 9x13-inch baking dish.
Melt butter in a large skillet over medium heat. Add onion and cook until soft. Add garlic and cook 1 more minute.
Add chicken, Alfredo sauce, sour cream, salt, pepper, and Italian seasoning. Stir and cook for 5 minutes.
Spread 1/3 of the chicken mixture into the baking dish. Top with 3 lasagna noodles. Repeat layers twice, ending with the remaining sauce.
Sprinkle mozzarella and Parmesan cheese over the top.
Cover with foil and bake for 30 minutes. Remove foil and bake another 10-15 minutes until cheese is bubbly and golden.
Let sit for 10 minutes before serving.