How to Make It
Add olive oil to a deep, 10-inch skillet.
Add garlic, crushed red pepper, and black pepper to skillet; place over medium heat. (This will heat oil slowly, and allow garlic to bloom without burning.) Once garlic is sizzling, cook, stirring occasionally, until slightly softened and fragrant, but isn’t browning, about 1 minute, 30 seconds.
Add vinegar to skillet, and stir. Cook until slightly thickened and reduced, about 1 minute.
Add beans; cook, stirring once or twice, until beans start to brown in places, about 5 minutes. Stir in water and salt.
Increase heat to medium-high until boiling; reduce heat to medium, and simmer until beans are very tender, about 5 more minutes.
Reduce heat to medium-low, and add spinach by the handful, letting it wilt slightly before adding the next handful. Cook, stirring gently, until spinach is fully wilted and incorporated into bean mixture. Stir in Parmesan; remove from heat. Stir in lemon juice.
ADD PASTA: Cook 6 ounces of pasta according to package instructions in heavily salted water. Reserve 1 1/2 cups of pasta cooking water; use cooking water in place of water and salt in step 4. Add cooked pasta right before adding greens.
ADD SAUSAGE OR OTHER GROUND MEAT: In step 1, reduce amount of olive oil to 1 tablespoon. Cook 6 ounces Italian sausage, or any other ground meat (such as ground pork, lamb or beef) over medium heat, stirring to crumble, until deeply golden brown, about 11 minutes. Proceed to step 2.
ADD BACON OR PANCETTA: Cut 2 pieces of thick-cut bacon into batons, or use 4 to 6 ounces diced pancetta. In step 1, reduce amount of olive oil to 1 tablespoon, and cook bacon or pancetta until deeply golden brown, about 8 minutes. Proceed to step 2.
USE A HEARTIER GREEN: Start with 1 bunch Tuscan kale, chard, collards, or broccolini rabe. Strip leaves off tough stalk, and tear leaves into bite-sized pieces. Thinly slice stalks. Add sliced stalks when adding beans. Add leaves in place of spinach, and allow another 1 to 2 minutes cooking time.
MAKE INTO SOUP: Double amount of liquid and salt. You can also substitute in homemade or store-bought chicken stock. (If you’re using homemade, make sure that it is on the salty side, as the liquid here is the seasoning agent for the whole dish.)