Step 1

Arrange 2 racks to divide the oven into thirds and heat the oven to 400ºF.

Step 2

Peel off and discard the excess papery skins from 1 medium head garlic, then slice a thin layer off the top to expose the cloves. Place on a piece of aluminum foil. Drizzle with 1 teaspoon of the olive oil and sprinkle with a pinch of kosher salt. Wrap the garlic completely in the foil. Roast on the upper rack of the oven for 25 minutes. Meanwhile, remove and trim the stems stems from 1 pound mushrooms if needed. If not already sliced, tear the caps into bite-sized pieces and place on a rimmed baking sheet.

Step 3

Drizzle the mushrooms with 2 tablespoons of the olive oil, and sprinkle with 1/2 teaspoon of the kosher salt and 1/4 teaspoon of the black pepper. Toss to coat, then spread out in an even layer. Transfer to the lower rack of the oven. Roast until the mushrooms and garlic are tender and caramelized, tossing the mushrooms halfway through, 15 to 20 minutes total.

Step 4

While the mushrooms are roasting, bring a large pot of salted water to a boil. Rinse and drain 2 cups farro. Add the farro to boiling water and cook until tender but still firm to the bite (it should not be fully cooked at this stage), 15 to 20 minutes. Meanwhile, place 4 cups broth in a small saucepan and bring to a simmer over medium heat. Reduce the heat and maintain a bare simmer. Mince 1 medium shallot and coarsely chop 2 tablespoons fresh thyme leaves. Finely grate 2 ounces Pecorino Romano cheese (about 1 packed cup); set aside.

Step 5

Once the mushrooms and garlic are roasted, remove from the oven and set aside until the garlic is cool enough to handle, about 5 minutes. Squeeze the cloves out of their skins into a small bowl. Mash with a fork until you have a mostly smooth purée (a few lumps are okay).

Step 6

Drain the farro. Return the now-empty pot to medium heat and add the remaining 1 tablespoon olive oil. Add the shallot and half of the thyme and sauté until the shallot is softened and translucent, 2 to 3 minutes. Add the farro, remaining 1/2 teaspoon kosher salt, and remaining 1/4 teaspoon black pepper. Cook, stirring often, until the grains smell lightly toasted, about 1 minute.

Step 7

Add 1/2 cup dry white wine and simmer, stirring constantly and scraping up any browned bits from the bottom of the pan with a wooden spoon, until the wine has evaporated and the pot is almost dry, about 1 minute. Incrementally add the broth about 1/2 cup at a time. Simmer, stirring constantly, and wait until the liquid has been almost completely absorbed before adding the next ladle. Continue adding the broth until the farro is al dente and the broth is creamy, 8 to 10 minutes total (you likely will not use up all the broth).

Step 8

Remove the pan from the heat. Add the roasted mushrooms, garlic purée, 1 tablespoon unsalted butter, and half of the grated cheese. Serve immediately, with the remaining grated cheese and thyme sprinkled on top of each bowl.