Preheat oven to 425 degrees F. Coat the bottom and sides of a roasting pan with nonstick cooking spray. Arrange squash in the bottom of the prepared pan. Drizzle with melted butter; toss to coat. Bake for 10 minutes, stirring once. Remove from oven. Add corn, onion, and leek to pan. Toss to combine. Return to oven and bake about 15 minutes more or until vegetables are tender, stirring once.
Place one-third of the squash mixture and one-third of the broth in a food processor or blender. Cover and process or blend until almost smooth. Repeat with half of the remaining squash mixture and the remaining broth at a time. Transfer processed mixture to a 4-quart Dutch oven. Add the half-and-half, snipped sage, and white pepper. Heat through.
To serve, ladle chowder into bowls. If desired, drizzle a little honey over individual servings. Garnish with fresh sage leaves.