Using the microwave to partially cook squash before placing it in the oven reduces the time it takes to cook squash.
Heat oven to 400 degrees F.
Wash whole squash. Pierce skin in several places with a sharp knife or metal skewer. Place on a paper plate to catch any drips. Cook whole in an 1100-watt microwave oven set at HIGH (100% power) for 4 minutes 5 seconds per pound.
Let squash stand until it is just cool enough to handle. Cut half-cooked squash in half, in quarters if it is very large. Scrape out seeds and fiber. Place squash pieces, cut side up, in a flat baking dish. Put a pat of butter in the cavity of each squash piece. Rub the butter around the cut surfaces of the squash to grease. Grind on some black pepper.
Place squash in oven and bake for 1/2 hour, until squash looks translucent and the flesh is easily pierced with the point of a knife.