How to Make It
In a medium saucepan, cover the farro with 2 inches of water, season with salt and bring to a boil. Cover and cook over moderately low heat until the grains are al dente; drain and return to the pot.
Meanwhile, in another medium saucepan of boiling salted water, cook the beans until crisp-tender, 5 minutes. Drain and pat dry. Cut the beans into 1-inch lengths.
In a large skillet, melt the butter. Add the garlic and mushrooms and cook over moderately high heat, stirring occasionally, until the mushrooms are lightly browned, about 8 minutes. Add the beans, season with salt and pepper and cook until just heated through.
Stir the mascarpone and chives into the farro and season lightly with salt and pepper. Spoon the farro into bowls, top with the mushrooms and beans and serve.