Preheat oven to 350 degrees. Coat a 9” square pan with cooking spray.
Place onions in a small microwave-safe bowl or plate. Cook for 1-2 minutes, until soft.
In a large bowl, add cooked onions, ricotta cheese, chicken, egg, egg white, and thawed corn. Mix well.
In another small bowl, mix together pasta sauce and Buffalo wing sauce. Spread ½ cup of sauce on the bottom of pan.
Arrange 3 tortillas (12 pieces) on top of pasta sauce.
Spread ½ of ricotta/chicken mixture over tortillas. Spread evenly using fingers or a rubber spatula.
Spread ½ cup of pasta/buffalo wings sauce, evenly over top.
Arrange 3 more tortillas (12 pieces).
Spread remaining ricotta/cheese mixture evenly over the tortillas. Spread all around, using your fingertips or rubber spatula.
Top with remaining sauce.
Cover the pan with foil and bake for 30 minutes.
Remove cover, sprinkle with shredded cheese. Cover and bake for 15 more minutes.
Cool slightly and cut into 6 slices. Top each slice with a dollop of fat-free sour cream or yogurt, if desired.