How to roast a head garlic: Preheat oven to 400°. Slice the top of a head of garlic off ( about a 1/4 slice) so that the tops of the garlic cloves are exposed. Place onto a square sheet of foil. Drizzle with about 1 tsp of olive oil. Wrap up the head of garlic in the foil. Place directly onto rack on a baking sheet. Bake for 35 to 50 minutes. Remove from oven, let cool before handling. Squeeze cloves into a bowl and mash before adding to soup.