Preheat the oven to 400°F. Place the squash pieces on a baking tray and bake for 35-45 minutes, or until very tender. Remove and cool to lukewarm.
Place the squash, salt and butter in the blender jar and pulse 2-3 times. Press 1 and blend until creamy and smooth.
Store in the refrigerator in single, meal-sized plastic containers. Seal tightly. Warm in the microwave oven before serving. After serving, discard any uneaten portion.