Potato Leek Soup

INGREDIENTS

• 1 1/2 teaspoons finely chopped fresh thyme
• Salt and freshly ground pepper
• 4 leeks (whites only), thoroughly washed and sliced
• 3 stalks celery, roughly chopped
• 8 cups chicken stock
• 1 bay leaf
• 6 russet potatoes, peeled and cut into large pieces
• 1 cup heavy cream