Cut the tops from the heads of garlic with a sharp knife, exposing the very tops of the cloves. Place each head on a square of aluminum foil large enough to encase the garlic. Drizzle half of the olive oil over the exposed tops of the cloves. Sprinkle the tops with salt. Wrap each head tightly in foil, and place them on a baking sheet.
Bake for about 45 minutes until the garlic is very soft. Let cool in the foil. When cool enough to handle, unwrap and squeeze out the roasted garlic from the papery wrapper, pressing up from the bottom to pop it out.
See above for info on how long to keep and how to use!