Meanwhile, in 10-inch nonstick skillet, cook sausage, mushrooms and onion over medium-high heat 5 to 7 minutes, stirring frequently, until sausage is no longer pink; drain. Stir in sweet potato and water; heat to boiling. Reduce heat; cover and simmer 6 to 7 minutes or until vegetables are tender. Uncover; cook 2 to 3 minutes longer or until liquid is evaporated. Remove from heat; stir in 1/2 cup of the cheese. Spoon into partially baked crust.