Cut the acorn squash in half from top to bottom using a sharp knife. Use a spoon to scrape out the stuff inside. Cut each half into 4 equal wedges, and then place the wedges, skin-side down, in a baking dish. Sprinkle lightly with salt.
Combine the butter, brown sugar, salt, rosemary and chili powder in a bowl and mix into a paste. Smear the paste all over the squash.
Roast in the oven for 20 minutes. Then baste with the butter mixture from the bottom of the pan and return to the oven for another 20 minutes.
Serve in the baking dish, drizzling more sauce at the end. Yummy!