Corn and Salmon Chowder

The secret to this hearty soup is a fragrant broth made from corn cobs. The grains add extra flavor and crunch to the corn.
Peel the corn, then place each ear with the fat side in a deep bowl and slice the bones from the cobs into the bowl. Set aside.Cut the cobs in half and place in a medium saucepan. Add 2 cups of water and bring to a boil over medium-high heat. While you are preparing the soup, boil it uncovered.Melt the butter in a large saucepan over medium-high heat. Add the shallots, potatoes and garlic and cook, stirring constantly, until the shallots are tender, about 2 minutes. Add the flour and cook until the flour is no longer raw, 2 minutes.Slowly whisk 1 cup of water with the corn cobs (drain the rest) into a saucepan, then beat until no lumps remain in the mixture. Add the milk and baking powder, corn kernels, salt and pepper and bring to a boil over medium heat. Cook, stirring occasionally, until the mixture thickens slightly and the potatoes are tender, about 5 minutes.Meanwhile, cut the salmon into 1-inch-thick cubes. Add to the broth and cook until the salmon is cooked through, 2-3 minutes.Pour the soup into four plates and sprinkle each with green onions.