Melt the butter in a pot set over medium heat. Add the squash, onion and garlic and cook 3 to 4 minutes. Mix in the flour and curry powder and cook 2 minutes more. While stirring steadily, slowly pour in the stock. Simmer for 10 to 15 minutes, or until the squash is very tender. Purée using a food processor, blender, or a hand-held immersion blender. Return the soup to a simmer; season with salt and pepper and reserve on low heat.
Heat a stovetop or electric non-stick grill to medium-high heat. Toss the scallops with the oil, salt and pepper. Grill one minute per side, or until just cooked through. Ladle the soup into heated bowls and fan four scallop halves on top of each. Sprinkle with parsley and serve.
Note: 1-1/2 to 2 lbs. of cleaned (seeds removed) squash will yield the 4 cups of cubed squash required for this recipe.