Heat a large Dutch oven over medium-high heat until hot. Add spinach; cover and cook 2 minutes or until spinach wilts. Remove spinach from pan. Drain.
Add 2 teaspoons oil to pan and place over medium heat until hot. Add onion and garlic; sauté 5 minutes. Add spinach; sauté 3 minutes. Place spinach mixture in food processor; pulse 10 times or until finely chopped. Combine spinach mixture, ricotta, Parmesan, 1/4 teaspoon salt, 1/4 teaspoon pepper, and egg white in a medium bowl.
Working with 1 won ton wrapper at a time (cover remaining wrappers with a damp towel to keep them from drying), spoon 1 1/2 teaspoons spinach mixture into center of each wrapper. Moisten edges of dough with water; fold in half, pinching edges together to seal. Place filled won tons on wax paper in an airtight container; chill for 2 hours.
After won tons have chilled, heat 1 teaspoon oil in a saucepan over medium-high heat. Add tomatoes; cook 5 minutes, stirring frequently. Stir in basil, 1/8 teaspoon salt, and dash of pepper; cook 5 minutes. Keep warm.
Cook filled won tons in batches in boiling water until they float to the surface (about 3 minutes); remove with a slotted spoon, and keep warm. Spoon tomato sauce over pasta.