2 tablespoons olive oil
1 large shallot, thinly sliced (about 1/2 cup)
Kosher salt and freshly ground black pepper
½ tablespoon dried red chili flakes, plus more to taste
2 medium cloves garlic, thinly sliced
1 bunch broccoli rabe, stems trimmed and the rest cut into 2-inch-thick pieces (about 6 cups)
4 cups homemade or store-bought low-sodium chicken stock
3 cups quinoa, spelt, or farro penne pasta
2 tablespoons fresh squeezed lemon juice from 1 lemon