In a medium saucepan over medium heat, melt butter. Add mushrooms, carrot and onion; cook and stir 2-3 min. Add rice; cook and stir 2-3 min. Add bouillon cube and water; bring to boil, stirring to dissolve cube.
Cover, reduce heat and simmer 15-18 min or just until rice is tender-firm and creamy. Stir in parsley and cheese. Serve immediately, with additional Parmesan if desired.