Toss cooked spaghetti with oil in a large bowl; add sauce, vegetables, mozzarella, garlic and seasonings. Mix well; spread in a lightly greased 13"x9" baking pan.
Whisk together eggs and milk; pour over spaghetti mixture. Arrange pepperoni evenly on top; sprinkle with Parmesan.
Bake, uncovered, at 375 degrees for 25 to 30 minutes, until bubbly and golden. Let stand for 5 minutes; cut into squares.