Preheat oven to 425 degrees F. Lightly grease a baking sheet. Prepare squash by slicing into chunks leaving the skin on and removing seeds, the smaller the chunks, the less cooking time required. Drizzle olive oil over flesh of the squash and spread with a spoon or hand for even coverage.In preheated oven, place squash cut sides down on the prepared baking sheet, and roast for 30 minutes, or until a sharp knife can be inserted with only a little resistance. Keep an eye on the squash to prevent burning of the skin. Remove squash from oven, Add salt and pepper to taste. Serve with the skin which should be tender enough to be eaten.