1. Preheat oven to 350°.
2. In a medium bowl, combine ricotta, 2 tablespoons pesto, and egg white; stir well.
3. Heat 1 tablespoon water in a medium skillet over medium heat; cook spinach until wilted (about 2 minutes), stirring well.
4. Spread remaining 2 tablespoons pesto in an 8-inch square baking dish; top with 6 wontons, overlapping slightly. Layer half of ricotta mixture evenly over top of wontons; add half of peppers over ricotta mixture.
5. Top peppers with another 6 wontons, remaining ricotta mixture, half of spinach, and remaining peppers. Top peppers with remaining 6 wontons and spinach. Sprinkle with mozzarella and Parmesan; cover tightly with foil.
6. Bake lasagna, in middle of oven, until cheese is melted and bubbly (about 20 minutes). Let stand 10 minutes. Cut into 6 equal-size pieces.