Potato, Leek, and Spinach Soup

Potato-leek soup has a well-earned spot in the French cooking canon. Served warm in the winter or cold in the summer, it’s a simple, economical favorite across the country. We eat it all winter because it’s warming, hearty, and nutritious, and all three of the kids love it. We make ours with spinach, for a vibrant final color that stays bright because we add the greens at the very last minute.

For a heartier style of soup, you can serve it without blending. In that case, skip the sp