No roasted garlic on hand? Two options! Slice the top 1/4 off a head of garlic. Place on a sheet of aluminum foil, drizzle with oil, salt and pepper. Twist up foil and pop in the oven as soon as you turn it on. Or, leave the cloves in the skin and roast up with the mushrooms and onions...then just pop (carefully!) cloves out of the skin.