- 1 pound fresh asparagus, trimmed and peeled
- 5 tablespoons unsalted butter, divided
- 5 cups chicken broth, divided
- 2 leeks, white and light green parts only, thinly sliced
- 1 pound fresh spinach, stemmed, divided
- 1 teaspoon white sugar
- 2 1/2 tablespoons all-purpose flour
- 1/4 teaspoon salt
- 1/8 teaspoon ground white pepper
- 1 cup frozen green peas
- 1/2 cup heavy whipping cream, or more to taste
- Cut asparagus stalks into 1-inch pieces; reserve tips in a bowl.
- Melt 2 tablespoons butter in a Dutch oven over medium heat. Add 1/3 cup chicken broth and leeks; cover and cook until leeks are tender, about 5 minutes. Add asparagus stalks; cover and cook for 3 minutes.
- Pour remaining 4 2/3 cups chicken broth into the Dutch oven. Bring to a boil; reduce heat and simmer until asparagus is very tender, 10 to 12 minutes. Add 2 packed cups spinach and sugar; cook until spinach is tender, about 5 minutes.
- Puree soup with an immersion blender until very smooth.
- Heat remaining 3 tablespoons butter in a small saucepan. Whisk in flour until well blended; cook for 1 minute.
- Whisk flour mixture into the pureed soup until smooth and blended. Season soup with salt and white pepper. Bring to a boil; reduce heat and stir in peas. Simmer until peas are barely tender, about 3 minutes. Stir in asparagus tips; simmer until tender, about 5 minutes.
- Pour heavy cream into the soup. Cook until heated through but not boiling, 3 to 4 minutes. Stir in remaining spinach; cook until heated through, about 3 minutes.