Preheat the oven to 425°.
Remove any loose pieces of the papery outer layer from the head of garlic. Cut about 1/2 inch off the top of the head to expose the cloves.
Make a pouch with aluminum foil and insert the head of garlic. Drizzle with 1 tablespoon of olive oil and sprinkle with sea salt. Seal the top of the pouch by rolling the foil down. Place on a baking sheet and cook in the preheated oven for 30 to 45 minutes or until the garlic is soft and has taken on some golden color on the top. Once cool squeeze the cloves out of the papery exterior.
For complete details see this Food Network guide. Try topping focaccia with roasted garlic.