Turn your stove on medium low heat. Melt butter in the pot and throw in your bay leaf, garlic, and leeks. Add salt and black pepper per taste.
After 2 minutes, add in the turmeric, and olive oil. Mix well and let the leeks cook down so they are soft (about 8 minutes).
Then, add in your potatoes and mushroom stock. Give it a mix. Add some more salt and give it a taste. Let this cook on your stove until the potatoes are completely cooked through. Will be about 25 minutes. (Adjust stove to medium if needed).
Once the potatoes are cooked through, take out the bay leaf. Use an immersion blender or a regular blender to puree your soup. Put it back on the stove, add in your milk, and let it simmer while you make the chili & chive grilled cheese. If you want it to be thinner, add more milk.