Heat olive oil on low heat in large pot. Add sliced leeks and saute until fragrant and softening, 3-4 minutes. Add potatoes, broth, water, bay leaves, and rosemary and bring to a gentle boil. Reduce to a simmer, cover pot and let cook for 20-30 minutes until potatoes are easily mashed.
Add coconut milk if using, nutritional yeast, lemon juice, salt and pepper to taste, and blend until creamy, using either an immersion blender, or regular blender in batches. Serve and enjoy!