This recipe can be made ahead—just wait to stir in spinach until after you reheat the soup.
1 tablespoon extra-virgin olive oil
1/4 cup chopped pancetta (about 1 ounce)
1 1/4 cups chopped onion
3/4 cup chopped celery
3/4 cup chopped carrot
1 teaspoon chopped fresh thyme
1 bay leaf
1 cup dried brown lentils
3 cups fat-free, lower-sodium chicken broth
2 cups water
1 (6-ounce) package fresh baby spinach
1/2 cup chopped fresh basil
1/4 cup (1 ounce) grated fresh Parmesan cheese
1 tablespoon fresh lemon juice
1/8 teaspoon freshly ground black pepper
How to Make It
Heat a Dutch oven over medium heat. Add oil to pan; swirl to coat. Add pancetta; cook 1 minute or until pancetta begins to brown, stirring occasionally. Add onion and next 4 ingredients (through bay leaf); cook 8 minutes or until vegetables are tender, stirring occasionally. Add lentils, broth, and 2 cups water; bring to a boil. Cover, reduce heat, and simmer 40 minutes or until lentils are tender and mixture is slightly thickened. Remove from heat. Discard bay leaf.
Place 2 cups lentil mixture in a blender. Remove the center piece of blender lid (to allow steam to escape), and secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters), and blend until smooth. Return pureed lentil mixture to pan. Add baby spinach, chopped basil, Parmesan cheese, lemon juice, and black pepper; stir until spinach wilts. Serve immediately.