Prepare noodles according to package directions; drain and set aside. Sauté Italian sausage, onion and garlic in a skillet until sausage is browned; drain. Add pasta sauce to sausage mixture and set aside.

In medium bowl, blend ricotta cheese, egg and 1/4 cup of Parmesan cheese and set aside.

Coat a 9 x 13-inch baking dish with non-stick spray and spread 1 cup sauce mixture on the bottom. Top with 3 lasagna noodles. Spread 1/4 cup ricotta cheese mixture on noodles and layer on 1 cup sauce mixture. Sprinkle 1 cup spinach and 1/2 cup mozzarella cheese. Repeat this whole process 3 more times starting with the noodles; top with 1/4 cup Parmesan cheese to finish.

Bake uncovered in a 350°F oven for 45 minutes until hot and bubbly. Let stand 10 minutes before cutting.