In fall and winter, markets overflow with spinach, kale, chard, and more greens, promising vitality and a slew of vitamins in every leafy bunch. For starters, these nutritional giants are loaded with vitamins A and C, folic acid, and calcium. Then there’s vitamin K (important for blood clotting and healthy bones), and phytochemicals that help protect against heart disease and cancer, and encourage healthy eyes. On the eating end of the equation, cold weather turns leafy greens milder, sweeter, and so tasty you just might want seconds.