Ingredients

• 2 1/2 tablespoons butter
• 1 leek (white part only), chopped
• 1 (10 ounce) package frozen chopped spinach, thawed and drained
• 6 tablespoons all-purpose flour
• 9 cups chicken broth
• 2 cups cubed fully cooked ham
• 1 ham bone (optional)
• 2 cups plain yogurt
• 2 egg yolks
• 1 pinch salt and ground black pepper to taste

Instructions

1. Heat butter in a stockpot over medium heat; cook and stir leek and spinach until leek is tender, 5 to 10 minutes. Stir flour into leek mixture and cook over medium-high, stirring constantly, until mixture flour is dissolved, about 2 minutes. Remove stockpot from heat.
2. Mix broth, ham, and ham bone into leek mixture; cook, stirring occasionally, over low heat until soup is slightly thickened, about 15 minutes.
3. Blend yogurt, egg yolks, salt, and pepper together in a blender or food processor until smooth; carefully stir into soup. Cook soup until heated through, about 5 minutes more. Remove and discard ham bone.