Preheat oven to 425°. In a large bowl, combine the vegetables, oil and cumin; toss to coat. Arrange in a single layer in an ungreased 15x10x1-in. baking pan. Bake, uncovered, until tender, 10-15 minutes. Reduce heat to 350°., Divide vegetable mixture evenly between 2 tortillas. Sprinkle with cheese. Top with remaining tortillas. Place on an ungreased baking sheet; bake until cheese is melted, 8-10 minutes. , Cut each quesadilla into 6 wedges. If desired, garnish with guacamole, sour cream, salsa and olives.