Set oven racks at the two lowest levels.

Oven: 450

Coat two baking sheets with vegetable cooking spray.

Peel away as much of the papery skin from the garlic as possible and wrap the head loosely in aluminum foil. Bake for 30 minutes, or until the garlic is very soft. Let cool slightly.

Arrange tomato, eggplant slices, zucchini, squash, onion, red bell peppers and yellow bell peppers on the prepared baking sheets. Roast for 20 miuutes, turning once, until just tender and browned. Let cool slightly.

Reduce oven temperature to 350 degrees.

Separate garlic cloves and squeeze the pulp into a large heavy saucepan or Dutch oven. Slip skins from the tomatoes and peppers. Slice all the vegetables into pieces and add to the garlic. Stir in basil, olive oil, thyme, oregano, bay leaves, salt and pepper.

Cover and bake, stirring occasionally, for 30 minutes, or until heated through and thickened. Remove bay leaves.

Taste and adjust seasonings, and serve hot or at room temperature.