Preheat the oven to 275 degrees. Remove the skin from the top half of each head of 6 heads of garlic, exposing the individual cloves. Arrange in a baking dish and dot with 1/3 cup of butter. Pour 1/3 cup of olive oil over and salt and pepper well. Put thyme sprigs here and there. Bake, covered, for 30 minutes, then take off the cover and baste every 15 minutes for an additional 1 to 1 1/2 hours depending on the size of the heads. The garlic should be very tender and sweet. I don’t know if they should be as brown as in the picture, but I quite enjoyed them that carmelized.
When the garlic is done, serve with the olive oil from the dish spooned over them. I went the extra mile and squeezed each clove out of the head onto a dish, spooned the oil out, and added the crisped thyme.
Served with peasant bread and soft white cheese, such as goat cheese or queso fresco.