Looks fancy. Tastes fancy. But it's so easy to make.
In large skillet, melt 1/2 stick butter over medium-high. Add mushrooms, garlic, and rosemary; season. Cook, stirring often, until tender, about 6 minutes; season. In saucepan, stir rice, wine, shallots, and remaining 1 stick butter over medium until wine is absorbed, 5 minutes. Stir in stock, 1 cup at a time, until absorbed, about 18 minutes. Stir in mascarpone; season. Top with mushrooms, Parmesan, and parsley.