Preheat the oven to 400°F. Optional: Line a baking sheet with parchment paper.
Halve acorn squash top to bottom. Scoop out seeds and stringy flesh.
2 medium acorn squash
Divide butter between squash halves, rubbing into the cut flesh with the back of a spoon. Sprinkle on the brown sugar and use the spoon to press it into the butter.
2 tablespoons salted butter, 2 tablespoons brown sugar
Place the squash cut-side up on the baking sheet. Roast in the oven for 30-40 minutes, until soft but not falling apart. Use tongs to carefully transfer to a serving dish or plate.
Notes
If using unsalted butter, add a small pinch of salt to each squash half.
Total roasting time will depend on the size of your squash.