Prepare the Corn: Remove the kernels from the ears of corn and set them aside in the refrigerator. Snap the corn cobs in half to prepare them for the broth.
Assemble Ingredients in the Slow Cooker: In a slow cooker with a capacity of 6 to 8 quarts, combine the halved cobs, prepared potatoes, chicken broth, canned green chiles, the whites of the scallions, garlic, butter, jalapeño, miso (if using), and kosher salt. Cook on the low setting for approximately 5 hours, or until the potatoes become tender.
Add Final Ingredients: Roughly 10 minutes before serving, remove and discard the corn cobs using tongs. Stir in the chilled corn kernels and scallion greens, allowing them to warm through in the hot chowder.
Incorporate the Cream: In a large bowl or liquid measure, whisk together the sour cream and heavy cream. Gradually whisk in a few ladlefuls of the hot broth to temper the mixture, ensuring a smooth blend. Stir the cream mixture into the chowder.
Finish and Serve: Season the chowder with additional salt and freshly ground black pepper to taste. Ladle the chowder into bowls and garnish with crispy bacon if desired. Serve immediately for best results.