Place both halves of the squash cut side up on a microwave-safe plate or dish. Put 2 tablespoons of butter, and 2 tablespoons of brown sugar into the cavity of each half.
Cook for 8 to 10 minutes in the microwave on full power. Rotate the squash a couple of times to ensure even cooking. When the flesh is soft, scoop out soft flesh with the sugar and butter, and place it in a bowl. Mash it a little to blend the ingredients. Serve in a bowl, or your could even serve it in the shells.
