1. Sauté all vegetables in oil for 10 minutes.
2. Mix milk, eggs, and salt. Add egg mixture to vegetables.
3. Preheat oven to 350 degrees Fahrenheit.
4. Alternate two layers of vegetable mixture and shredded cheese into each crust.
5. Place the pies into nine x 13-inch pans, cover, and bake at 350 degrees Fahrenheit, for 45 minutes. Uncover and bake another 10 to 15 minutes.