- 1 1/2 cups dried cannellini (white kidney) beans, soaked overnight, drained
- 1 head of garlic, halved crosswise; plus 2 garlic cloves, crushed
- 3 sage leaves
- 6 tablespoons olive oil, divided, plus more for serving
- Kosher salt
- 1/2 teaspoon crushed red pepper flakes
- 2 bunches mature spinach, trimmed
- 1 tablespoon finely grated lemon zest
- 2 tablespoons fresh lemon juice
- Bring beans, head of garlic, sage, 3 Tbsp. oil, and 6 cups water to a boil in a large saucepan over medium heat. Reduce heat, add several generous pinches of salt and simmer gently until beans are creamy all the way through but skins are still intact, 35–45 minutes. Let cool.
- Heat 3 Tbsp. oil in a large skillet over medium. Cook crushed garlic and red pepper flakes, stirring, just until garlic is golden, about 1 minute. Working in batches, add spinach, letting it wilt slightly before adding more, and cook, tossing often, until leaves are just wilted, about 5 minutes; season with salt.
- Using a slotted spoon, transfer beans to skillet with spinach and cook, tossing gently, until beans are warmed through. Add lemon zest, lemon juice, and 1/4 cup bean cooking liquid and toss, adding more cooking liquid if needed, until coated (mixture should be saucy but not submerged in liquid; don’t cook too long or beans will get mushy). Taste and season with salt. Serve drizzled with oil.
- Beans can be cooked 3 days ahead. Keep in cooking liquid; cover and chill.