1. Melt butter in a saucepan set over medium heat. Add onion and cook until soft, 4 minutes. Add stock, water, jalapeño and reserved corncobs; simmer for 20 minutes. Remove cobs and discard.
2. Add corn kernels and potato. Simmer until potato is tender, 15 minutes. 3. Stir in cream and milk; season to taste.
4. Ladle soup into bowls, top with spring-onion greens and serve.
NUTRITIONAL INFO PER SERVING
(11/2 cups) 729 kJ (174 cal), 5g protein, 32g carbs, 4g fibre, 5g fat (2g sat fat), 252mg sodium