Slice the squash in half and remove the seeds. The seeds can be roasted later.
Place the squash cut side up on a sheet pan lined with parchment paper
Season with kosher salt and place into the oven for 20 minutes or until it can be pierced with a fork.
To make the butter
Place half a Hatch chile, seeds removed into a food processor with 1 stick of butter cut into cubes. Process until smooth. You won't need all the butter, you can save it in the fridge or wrapped tightly in the freezer.
To finish the squash
Remove from the oven. Raise temperature to 450 degrees.
Brush on the Hatch Chile butter. Sprinkle with brown sugar.
Return to the oven for about 5 minutes or until the sugar has melted and caramelized. Keep a careful eye on it so that you don't burn the sugar.