Making Best Potato Leek Soup can be a smooth process if you follow these steps:

1. Prepare the Leeks: Clean the leeks under cold running water, ensuring all dirt is removed. Slice them thinly.
2. Melt the Butter: In a large pot, melt the butter over medium heat.
3. Sauté Aromatics: Add the sliced leeks and chopped onion to the pot. Sauté until softened, about 5-7 minutes. Stir occasionally to prevent browning.
4. Add Potatoes: Once the leeks and onion are tender, add the diced potatoes and stir together for another minute.
5. Pour in Broth: Add the vegetable or chicken broth to the pot. Ensure the potatoes and leeks are submerged.
6. Season: Stir in the salt, black pepper, and thyme (if using). Bring the mixture to a boil.
7. Simmer: Reduce heat and let the soup simmer for about 20-25 minutes or until the potatoes are tender.
8. Blend the Soup: Using an immersion blender, blend the soup until smooth. If you prefer a chunkier texture, blend until your desired consistency is reached.
9. Add Milk/Cream: Stir in the whole milk or cream to make the soup rich and creamy. Heat gently but do not boil.
10. Taste and Adjust: Taste the soup and adjust seasonings as necessary. Remove from heat when ready.
11. Garnish: Serve hot and garnish with fresh chives if desired.

Following these steps will lead you to a delightful pot of Best Potato Leek Soup, ready to warm your soul.