Preheat the oven to 400°F
Wash the acorn squash
Cut the squash in half lengthwise
Scoop out the seeds and stringy pulp
Place the squash halves cut-side up on a baking sheet
Brush or rub the flesh with oil or butter
Sprinkle with salt and pepper
Place the squash cut-side down on the baking sheet if you want softer flesh
Roast for 35 to 50 minutes
Check for doneness by piercing the flesh with a fork
Remove from the oven when the flesh is tender
Let cool slightly before serving
Scoop out the flesh or serve in the shells