Dice onion into small pieces, crush garlic. Cut leeks in half lengthways, finely slice and wash well, peel potatoes, and cut in quarters.
Heat pot, add oil, sweat onion and garlic for 2-3 mins, add pinch salt.
Add leeks, season with salt and pepper, sweat for 2-3 minutes.
Add potatoes, and vegetable/chicken stock to cover, bring to boil, and then reduce to simmer for 20 minutes, check seasoning, add a little more if required
Preheat grill, slice baguette on an angle, add grated parmesan on top.
Blitz soup with a hand blender until pureed smooth, return to heat, check seasoning and add cream, bring back to a boil and take off heat.
Grill parmesan baguette until golden.
Serve soup in bowls, sprinkled with chives, sea salt, freshly ground pepper, and parmesan croute.
TIP: Keep the potato skin on. Once you puree the soup the skin dissolves in the mixture. This saves time and it's healthier.