I start by washing the acorn squash under cool water, then slicing it in half from stem to base. I use a sturdy spoon to scrape out all the seeds and the stringy pulp in the center. If the skin feels slippery, I steady the squash on a damp towel while cutting so it doesn't slip.
I place both squash halves cut-side up on my baking sheet. Then I rub the softened butter generously over the flesh of each half, making sure it gets into every little groove. I sprinkle the brown sugar, cinnamon, salt, and pepper evenly over the top.
I preheat my oven to 400°F and roast the squash for about 50 to 60 minutes. I like to loosely tent the halves with foil for the first 30 minutes, then remove it so the tops get that gorgeous caramelized look. I check tenderness with a fork around the 45-minute mark.
Once the squash is fork-tender and the edges look slightly golden, I pull it out and let it rest for about 5 minutes. This little pause lets the caramelized sugar set a bit so it doesn't run everywhere when I serve it. Then I plate it up and dig in while it's still warm.