8 ounces whole-wheat shells, fusilli or chiocciole
1 large bunch broccoli rabe, trimmed and cut into 1-inch pieces, or 8 cups baby spinach
1 1/2 cups vegetable broth, or reduced-sodium chicken broth
1 tablespoon all-purpose flour
2 tablespoons extra-virgin olive oil
4 cloves garlic, minced
1 19-ounce can cannellini beans, rinsed
2 tablespoons red-wine vinegar
1/4 teaspoon salt
1/4 teaspoon freshly ground pepper
1/2 cup shredded fontina cheese
2/3 cup Toasted Breadcrumbs, optional
Bring a large pot of water to a boil. Add pasta and cook, stirring occasionally, according to package directions. Stir in broccoli rabe (or spinach) during the last 2 to 3 minutes. Drain. Dry the pot.
Whisk broth and flour in a small bowl until smooth. Heat oil in the pot over medium-high heat. Add garlic and cook, stirring constantly, until fragrant, about 30 seconds. Add the broth mixture and bring to a simmer, whisking constantly, until it thickens, 3 to 4 minutes. Add beans, vinegar, salt and pepper and the pasta and broccoli rabe (or spinach). Cook, stirring, until the mixture is heated through, about 1 minute. Remove from the heat; add cheese, stirring until it melts. Serve immediately, topped with Toasted Breadcrumbs, if using.