Start by peeling and dicing the potatoes into small chunks. Clean and slice the leeks, making sure to rinse them well between the layers. Chop the onion and mince the garlic. Having everything prepped and ready to go will make the cooking process quick and smooth.

In a large pot, heat the butter (or olive oil) over medium heat. Add the chopped onion and minced garlic and sauté for about 2-3 minutes until they become fragrant and soft. Then, add the sliced leeks and cook for another 5-7 minutes, stirring occasionally, until the leeks are tender and have softened.

Add the diced potatoes to the pot and stir to combine with the sautéed vegetables. Pour in the vegetable broth, making sure the potatoes are fully submerged. Bring the mixture to a boil, then reduce the heat to low and let it simmer uncovered for about 15-20 minutes, or until the potatoes are fork-tender.

Once the potatoes are soft, it’s time to blend. You can use an immersion blender directly in the pot for a smooth, creamy texture. If you don’t have an immersion blender, carefully transfer the soup in batches to a regular blender and blend until smooth. If you like your soup a little chunky, feel free to leave some pieces of potato intact.

After blending, return the soup to the pot if needed. Stir in the heavy cream (if using) for extra creaminess, and let the soup simmer for an additional 5 minutes. Taste and season with salt and pepper to your liking.

Ladle the soup into bowls and garnish with fresh parsley, if desired. Serve hot and enjoy the comforting warmth of this delicious, creamy potato leek soup!