1. In a large pot, heat the butter and oil over medium low heat. Add the leeks and garlic and cook, stirring, until the leeks are tender, about 15 minutes.
2. Add the potato cubes and cook another 5 minutes. Add the broth and celery salt. Bring to a simmer over medium heat. Cover and simmer until the potatoes are tender, about 30 minutes.
3. With a blender or food processor, puree the soup until smooth and creamy. Add the spinach and pulse to blend.
4. Season with salt and pepper.
Find any recipe, add your own, make grocery lists easily from recipes. Enter any 3 ingredients and BigOven will tell you what you can make. It's free! (4.5/5 stars)