In a large saucepan over medium heat, add shallots and sauté for 3 minutes. Add squash to pan and sauté for 8-10 minutes. Add soup, corn and greens to pan and bring to a low boil. Reduce heat and simmer for 15 minutes, stirring occasionally, until greens are wilted and squash is heated through. Add salt and pepper to soup and stir to combine. Spoon soup into bowls and serve with fresh, crusty bread for dipping.