Combine tomato and water in a small bowl; cover and let stand 15 minutes. Drain tomato, and set aside.
Clean mushrooms with damp paper towels. Remove mushroom stems; mince stems, and set aside. Coat a medium nonstick skillet with cooking spray; place over medium-high heat until hot. Add mushroom caps, and saute 5 minutes. Remove from skillet, and drain on paper towels; place caps on rack of a broiler pan coated with cooking spray.
Coat a nonstick skillet with cooking spray; add oil. Place over medium-high heat until hot. Add mushroom stems and garlic; saute until tender. Remove from heat; stir in tomato, breadcrumbs, and next 3 ingredients. Spoon tomato mixture into mushroom caps; sprinkle with Parmesan cheese. Broil 5 1/2 inches from heat (with electric oven door partially opened) 2 to 3 minutes or until cheese melts. Serve immediately.