Heat oven to 400 degrees.
Halve the peeled garlic clove and rub bottom of a large baking dish with the cut side of the garlic. Coat the bottom of the dish with 2 tablespoons oil. Arrange vegetables in dish, alternating them and overlapping them. Season with salt and pepper as you layer the vegetables. Scatter herbs on top and drizzle with remaining oil to coat generously. Add garlic cloves evenly over the top.
Bake 25 minutes, then baste vegetables with oil from pan, and continue baking until tender and browned, about 25 minutes more.