Sprinkle Eggplant With Salt And Let Sit For 30 Minutes. Pat Dry With Paper Towels. Heat A Heavy Skillet Until Very Hot And Then Add 1 Tablespoon Of The Olive Oil And The Eggplant, Unpeeled Garlic, And Onion Quarters. Reduce Heat And Cook Until Vegetables Are Lightly Charred. Remove From Heat And Let Cool To The Touch. Cook Zucchini In Boiling Water Until Tender About 15 Minutes. Drain And Let Cool. Preheat Oven To 375 Degrees. Peel Whole Garlic Cloves And Return Them To The Eggplant Mixture. Dice The Onion Quarters And Return To The Eggplant Mixture. Dice The Cooked Zucchini And Add To The Eggplant Along With Pepper, Tomatoes, Minced Garlic, Rosemary And Feta Cheese. Pour Into A Large Gratin Dish And Sprinkle With Grated Cheeses. Bake Until Lightly Browned On The Top. Serve.