1Set oven control to broil. Remove stems from mushroom caps; set stems aside. Place mushroom caps, stem sides down, in ungreased jelly roll pan, 15 1/2x10 1/2x1 inch. Broil with tops about 4 inches from heat about 8 minutes or until mushrooms begin to release moisture. Remove mushrooms from pan; drain on paper towels. Finely chop mushroom stems.
2Spray nonstick wok or 12-inch skillet with nonstick cooking spray; heat over medium-high heat until cooking spray starts to bubble. Add onion, gingerroot, garlic and sherry. Cook about 6 minutes, stirring frequently, until onion is tender. Stir in chopped mushroom stems and remaining ingredients. Heat through.
3Place mushroom caps, stem sides up, in ungreased jelly roll pan. Spoon shrimp mixture into caps, mounding slightly. Spray lightly with nonstick cooking spray. Broil with tops 4 inches from heat about 5 minutes or until shrimp mixture is light brown.