Place butter in 9-inch square glass baking dish. On HIGH: Melt butter. Add mushrooms, onions and garlic. Stir to coat. Cook, uncovered, for 5 minutes.
Add rice, chicken broth and wine (if used). Cook uncovered, until rice is tender (about 20 to 30 minutes). Stir once halfway through cooking. If rice isn't moist enough, add more broth towards the end.
Remove from microwave. Stir in Cheddar. Let stand 5 minutes.