1) If using an oven follow these directions: Heat oven to 435F (225C). Place stuffed mushrooms in a deep roasting pan. Cover roasting pan with tin foil and roast in oven (middle rack) for 12-15 minutes or until mushrooms are tender. 2) The uncooked mushroom mixture will taste very salty and overwhelmingly like garlic. Once stuffed mushrooms have been roasted or grilled the flavor will become much milder. 3) Canned peas can also be used in place of frozen peas. Please rinse canned peas thoroughly before using.