Step 1

Preheat oven to 375°F. Coat a 13- X 9-inch baking dish with cooking spray.

Step 2

Cook farro in salted water according to package directions; drain any liquid not absorbed (you should have about 6 to 6 1/2 cups; pearled/semi-pearled farro cooks in 20 to 30 minutes while whole farro cooks in 60 minutes - check your package carefully). Place farro in a large bowl; fluff with a fork.

Step 3

In a large deep skillet, heat oil over medium heat. Add squash, shallots, red pepper and garlic; cook, stirring frequently, until shallots and pepper are softened, about 5 minutes. Add 3 tablespoons sage and cayenne; cook, stirring frequently, about 3 minutes.

Step 4

Add spinach; cook, stirring frequently, until spinach is wilted, about 2 minutes. Add squash mixture to farro; toss to combine. Stir in broth, lemon zest, lemon juice, salt and pepper; stir in Gruyere and spoon mixture into prepared pan.

Step 5

In a small bowl, combine walnuts, Pecorino and remaining 2 tablespoons sage; sprinkle evenly over farro mixture. Cover with foil and bake for 15 minutes; uncover and cook until casserole is heated through and top is lightly browned, about 5 minutes more. Yields about 1 heaping packed cup per serving.