In a pot of cold water over high heat, boil the potato in its skin until just cooked, drain, then set aside to cool.
In a mid-sized soup pot over medium, heat the oil and fry the onion until soft, add the bay leaf and garlic and fry until the fragrant, then add the corn kernels, salt and pepper, and continue frying until the kernels darken in colour. Reduce heat and remove a tablespoon of corn kernels and set aside.
To the soup pot, add 500ml water, the curry powder, ground turmeric, and parmesan rind, cover, and bring to a boil. Meanwhile, peel and dice the potatoes, add half to the pot, cover, turn the heat to low to reduce to a simmer.
Use a handheld potato masher to crush the potatoes and corn, or an immersion blender to purée the potatoes and corn, leaving around half the corn kernels whole so the soup has some texture.
Add the remaining diced potatoes, increase the heat to high and bring to a boil again so it’s piping hot. Taste, and adjust the seasoning and spices to your palate.
In a small frying pan over medium heat, melt the butter, add the white scallion/spring onion bulbs and white parts of the stalks and fry, stirring occasionally until soft and slightly charred, and sweet-tasting. Divide between the soup bowls.
Transfer the tablespoon of corn kernels you set aside earlier to the same small pan and fry, stirring occasionally, until charred and smoky, then set aside.
Use a ladle to distribute the corn chowder between bowls, sprinkle on the croutons, charred corn, finely sliced green scallions/spring onions and grated Parmigiano Reggiano, drizzle on the extra virgin olive oil, crack some black pepper over bowls, and serve immediately with additional croutons, crostini or toast brushed with olive oil.