Cut the acorn squash in half, lengthwise and remove the seeds. Discard.
Place 2 tablespoon of butter and 2 tablespoon of brown sugar in each half.
Bake the squash for one hour or until flesh is soft. A larger squash may have to cook longer than an hour. After the first hour, check it in 10 minute increments until the flesh is soft (use a fork to test doneness - if the fork pierces the flesh easily, it is done).
Remove from oven and let cool for 5-10 minutes before serving. To eat, carefully scrape the flesh off the sides and mix with the melted butter and brown sugar, being careful not to punch a hole in the outer skin.
If you use unsalted butter, add ⅛ teaspoon of salt to each squash half - the salt helps bring out the flavor of the squash and sugar;
Pierce the inside flesh of the squash to determine doneness - if squash can be easily pierced it is done. Do not pierce through the skin as your roasting liquid will leak out.
To eat, carefully scrape the flesh off the sides and mix with the melted butter and brown sugar. Be careful not to punch a hole in the outer skin, otherwise you will lose all your sweet liquid.
If you do lose the liquid, heat 2 tablespoons of butter and 2 tablespoons of brown sugar in a bowl. Scoop the flesh and mix with the butter mixture - and you're set!