Heat oil in large sauté pan. Add mushrooms, onions and garlic and sauté until all liquid is cooked out of mushrooms. Remove from heat and cool slightly, then purée in food processor until smooth. Add to cream cheese and onion powder in medium-size bowl and mix with electric mixer until smooth. Add salt and pepper to taste.
NOTE: Mushroom mixture can also be roasted on a cookie sheet in a 425° F oven for 15 minutes. If roasting, eliminate oil.Makes 8 appetizers Source: