Preheat oven to 425°F / 200°C.

Cut off and discard about 1 cm from tops of garlic heads, making sure that all cloves are exposed. Put garlic in a baking dish with the olive oil, thyme, salt, and pepper and cover with a double layer of aluminum foil. Crimp the edges tightly.

Roast until the garlic bulbs are golden and tender, about 1 to 1 1/4 hours.

When garlic is cool enough to handle, squeeze cloves into a bowl (the cloves will pop right out of the paper skin when squeezed - and if you are impatient like I am then use a couple forks to hold and squeeze out the flesh).

Pour the oil through a fine-mesh sieve onto garlic. Mash well with a fork and season with salt.

Serve with ciabatta bread.