I like to think of this gratin as farro salad in autumn sweater form. It’s cozy, comforting, and not too heavy. It doesn’t require much effort, either--a dish that’s as fitting for a harried weeknight as a relaxed weekend dinner with friends.
Its basic formula is simple: cooked grains + dressing + vegetable (quick-cooking or cooked) + melty cheese + crumb topping. Using this formula, you can easily tailor the ingredients based on what you like and have on hand.
Tip: For ease, use the slicing blade of your food processor to shave the Brussels sprouts, and the shredding blade for the cheese. No need to clean the bowl of the food processor in between! —EmilyC
Heat oven to 400° F. Meanwhile, cook farro in a large pot of boiling salted water, skimming the surface a few times, until tender, 15 to 20 minutes—or according to package directions. Drain.
Toss grains while still warm in a large bowl (or back in the pan if it’s large enough for mixing) with 3 tablespoons olive oil, balsamic, and a pinch or two of salt. (The balsamic will taste a bit strong at this point, but it’ll mellow in the oven and help cut through the gratin’s richness.). Toss in Brussels sprouts, and season with 1/2 teaspoon of salt (or to taste) and Aleppo pepper. Add shredded cheese, and toss again until evenly mixed. Transfer to a lightly greased 14-inch round pan, a 9x13-inch casserole, or an equivalently sized dish.
In a small bowl, combine panko, pecorino, and several grinds of black pepper. Drizzle 1 tablespoon olive oil evenly over panko mixture (otherwise it’ll clump) and using hands, toss together until evenly mixed. Spread evenly over the farro and Brussels sprouts.
Bake for about 25 minutes, or until the crumbs are golden and crispy. Serve warm.