Pulverize the porcini in a food processor, then reconstitute in 3 cups of warm water. Set aside for at least 10 minutes.
Pour porcini water in a pot, salt the water, and bring to a boil. Stir in farro, lower heat to a simmer and cook until water is gone, about 40 minutes. Farro should be al dente yet tender. You can add more or less water and cook until desired softness. There's plenty of leeway and personal preference with farro.
While farro is cooking, saute chanterelles for several minutes in butter in a large skillet, in batches if necessary. Avoid slimy chanterelles by not crowding the pan. You want the mushrooms to be lightly browned and firm.
Stir mascarpone into farro, then stir in most of the chanterelles, reserving some as a topping. Season and garnish with chopped chives or parsley.
