Heat the oven to 375°F and spread 3/4 cup Alfredo sauce in a 9-by-13-inch baking dish.
Mix the ricotta, egg, spinach, 1/2 teaspoon salt and black pepper in a bowl.
Layer 3 noodles, one-third of the remaining sauce, half the ricotta mixture, half the chicken and 1/2 cup mozzarella in the dish.
Repeat the layers, finish with the last 3 noodles and sauce, and top with the remaining mozzarella and Parmesan.
Cover with foil and bake for 35 minutes, then uncover and bake until browned and bubbling, 12 to 15 minutes.
Rest the lasagna for 15 minutes before cutting it into squares.