Preheat the oven to 120C/250F/Gas 4.
Arrange the whole heads of garlic snugly in an oven dish. Drizzle with olive oil and season with thyme, salt and freshly ground black pepper. Roast in the oven for about an hour, or until the garlic is softened.
Squeeze the soft garlic out of its skins into a small dish or bowl. Add enough olive oil to make a thick paste and season, to taste, with salt and freshly ground black pepper. Slice some goats' cheese thinly. Cut the ciabatta in half and place under the grill to toast then spread the slices with the garlic paste. Place the goats' cheese on top and pop under the grill again until the cheese has melted.
Serve with on a bed of fresh, crisp lettuce leaves. I often add a couple of slices of prosciutto, too.