Preheat oven to 325. Oil a deep 2 quart (8 cup) baking dish. Heat 1/4 cup olive oil in large saute pan and cook onion slices very slowly until tender, but not brown. Remove from pan. Add the other 1/4 cup olive oil to the pan and saute eggplant, zucchini and squash until tender. Combine with the onion and season with salt, pepper and oregano. In the food processor, combine all ingredients for the batter. Place in a large bowl and combine with the cooked vegetables. Pour into the prepared pan and cover with foil. Bake for 45 minutes. Remove the foil and top with 2 tablespoons Parmigiano and bake for an additional 15 minutes or until set. Recipe by: Gilda Latzky (adapted from Union Square Cafe) Converted by MM_Buster v2.0n.