Cut eggplant into 1/4-in.-thick slices. Place in a colander over a plate; sprinkle with salt. Let stand for 30 minutes. Rinse under cold water and pat dry with paper towels.
In a shallow bowl, combine the bread crumbs, garlic salt and pepper. In another shallow bowl, beat eggs. Dip eggplant into eggs, then coat with crumb mixture.
In a large skillet, cook eggplant in 2 tablespoons oil for 2 minutes on each side or until lightly browned. Transfer to an ungreased 13-in. x 9-in. baking dish. In the same skillet, saute the green pepper, onion and mushrooms in remaining oil for 5 minutes or until pepper and onion are crisp-tender. Sprinkle over eggplant. Top with tomatoes.
Bake, uncovered, at 350° for 25 minutes. Place cheese slices over the top. Bake 25-30 minutes longer or until cheese is lightly browned.