In this case, I prefer steaming the squash- no need to turn the oven on and you can use the same pot you are going to cook the mac and cheese in. However, the flavor of roasting can be a nice addition, so use the cooking technique you prefer.
+ Recipe is a cross between my old butternut squash mac and cheese and White On Rice Couple's Stove Top Version. My instructions are paired down because I never had trouble with the recipe but I would recommend popping over to their site to read through their detailed instructions.
Find it online: https://todays-picks.store/stove-top-butternut-squash-mac-and-cheese/%3C/a%3E%3C/p%3E