Preheat oven to 400°F.: As the oven warms, you will notice a faint dry heat that helps create an even roast. A properly preheated oven prevents long periods of uneven cooking that can toughen the cloves. If your oven is cooler than the set temperature, the garlic will take longer and may not reach the desired caramelization; avoid opening the door frequently during preheat to keep the temperature steady.
Cut about 1/2 inch off the top of the head of garlic, exposing the individual cloves. Drizzle the top with olive oil, wrap in foil, and place in the oven for 35-40 minutes, until soft. Remove from the oven and allow to cool slightly; once cool enough to handle, squeeze the softened cloves into a bowl to use.: You will smell a warm, toasty sweetness as the sugars start to brown, and the head should feel tender when gently pressed. Wrapping in foil traps steam and allows the cloves to steam roast, producing a spreadable texture. One pitfall is cutting too deep into the cloves, which can dry them during roasting; slice just the very top to expose the tips.
Preheat oven to 400°F.: Warming the oven again ensures the small pouch will roast quickly and evenly. The consistent oven temperature gives the cloves a chance to develop golden edges while turning tender inside. Avoid placing the foil pouch on the bottom rack if the oven has hotspots, as that can lead to uneven color development.
Peel the garlic cloves. Place the cloves in a piece of heavy-duty foil – drizzle with a small amount of olive oil, then wrap in the foil, leaving a small opening at the top of the pouch. Place in the oven for 25-30 minutes, or until garlic is soft and starting to turn golden. Allow to cool.: As the cloves roast, they emit a sweet, almost hazelnut aroma and may glisten slightly where the oil contacts them. Leaving a small vent in the foil prevents excess condensation from pooling, which helps the edges caramelize. A common mistake is overcrowding the pouch, which can cause uneven cooking, so give the cloves room to roast in a single layer when possible.