Preheat oven to 400°F. Coat a 13x9x2-inch baking dish with cooking spray; set aside. In a small saucepan, combine the bulgur and 1/2 cup of the water. Bring to a simmer. Simmer, covered, for 12 minutes.
In a food processor, combine the bacon, green onions, bread, egg white, cheese, sage, salt, and pepper. Cover and process until it forms a rough paste.
Place mushrooms, stemmed side up, in the prepared baking dish. Stuff mushrooms with bulgur mixture.
Pour the other 1/2 cup of water into bottom of dish; cover with foil. Bake, 15 to 20 minutes or until hot. Uncover and bake 5 to 10 minutes more or until tops are lightly crisp. Let cook 5 minutes.