50g butter
2 leeks, trimmed, washed & sliced
2 celery stalks, chopped roughly
3 tsp fresh thyme leaves
1 garlic clove, minced
1.2kg sebago potatoes, peeled & chopped into small pieces
1L vegetable stock (see tip)
2 cups water
Sea salt Cracked black pepper
¾ cup cream, plus extra to drizzle
Crusty bread, to serve