Place the bacon pieces in a large Dutch Oven or soup pot over medium heat and cook until it's crispy and browned, about 10-12 minutes. Use a slotted spoon to transfer the bacon to a paper towel lined plate, leaving the fat behind in the pan.
Add the onion and celery into the bacon fat, cook over medium – low heat for 10 minutes, or until soft and translucent then add the curry powder, carrot, parsnip, apple and a generous pinch of salt. Sauté for 5 minutes, stirring frequently.
Next, add the chicken stock and bring the soup to a low simmer. Cover and let the soup cook until the carrots and parsnips are completely tender, about 20-30 minutes. Next, turn off the heat, pour in the cream and maple syrup then blend with an immersion blender (or in batches with a countertop blender, see notes below) until smooth. Taste and adjust the seasonings as needed.
To serve, divide the soup between bowls, top with sliced apple, bacon crumbles and a dollop of sour cream. Serve right away.