Combine the zucchini, yellow squash, leek, 1 tablespoon olive oil, salt, and pepper in a bowl, and toss well to coat. Spoon into a 2-quart baking dish lightly coated with nonstick cooking spray.

Combine 1 tablespoon olive oil, bread crumbs, cheese, thyme, and garlic in a bowl, and mix well. Sprinkle evenly over the vegetables.

Bake, covered, at 425° for 10 minutes. Bake, uncovered, for 10 minutes longer or until the vegetables are tender.

*To prepare leeks, trim so that only the white and pale green parts remain. Cut lengthwise, and rinse under cold, running water to remove sand and grit.