01 - In a medium saucepan, bring the vegetable broth to a gentle simmer and keep warm over low heat.
02 - In a large, heavy-bottomed skillet or Dutch oven, melt 3 tablespoons of the butter over medium heat. Continue cooking, swirling occasionally, until the butter turns golden brown and smells nutty (about 3–4 minutes).
03 - Add the chopped sage leaves and cook for 30 seconds until fragrant. Remove half the sage and set aside for garnish.
04 - Add the diced onion to the skillet and sauté for 3–4 minutes until translucent. Stir in the garlic and cook for 1 minute more.
05 - Add the farro and toast, stirring, for 2 minutes to coat the grains in the brown butter.
06 - Pour in the white wine and cook, stirring, until mostly absorbed.
07 - Begin adding the warm broth, one ladleful at a time, stirring frequently. Wait until most of the liquid is absorbed before adding more. Continue until the farro is tender but still chewy, about 30 minutes. (You may not need all the broth.)
08 - Stir in the remaining 1 tablespoon butter and the grated Parmesan cheese. Season with salt and pepper to taste.
09 - Remove from heat and let rest for 2 minutes before serving. Garnish with reserved crispy sage and extra Parmesan if desired.