As a vegetarian, I'm always looking for good sides to bring to any thanksgiving I attend to ensure that I'll have something to eat. This is one of my favorites, that always wins over the hearts of vegetarians and carnivores alike. In my college days, I would often use store bought frozen butternut squash puree which does make this recipe a whole lot easier. If you're going to make the swap, just buy two standard size (12-16 oz) boxes of frozen butternut squash puree and heat as per the directions on the package and follow from step 5. —DicedTomato
Cut squash in half, lengthwise. Scoop out sides and fibers surrounding seeds. Spray or coat lightly with vegetable oil and sprinkle cut side with salt. Place on a cookie sheet, cut side down, and roast for about 30-45 minutes until squash is fork tender and cooked through.
Remove from oven and allow to cool. When squash is cool enough to handle, scoop out flesh from skin and place in a food processor or blender.
In a food processor or blender, blend squash pulp until large chunks have disappeared. Make sure to allow some of the texture to remain. Think slightly chunky mashed potatoes not carrot soup.
Place the pureed squash in a large bowl and mix the pulp with the cream, cinnamon, nutmeg, and maple syrup.
At this point, you can store the mixture until you are ready to serve.
About 45 minutes before serving time, Preheat oven to 350 degrees again.
Pour squash mixture into a 9x13 casserole dish and smooth the surface. Place in oven and heat until warm throughout (a good serving temperature) this time will vary depending on how cold your mixture started. You don't want to cook it, just to heat it back up. To save time and oven space, this step could also be preformed in a microwave.
When the squash mixture is warmed through, remove it from the oven or microwave and set the oven to broil
Pinch off pieces of the butter and distribute butter bits along the surface of the casserole. Don't worry too much about perfect distribution, just try the best you can. Sprinkle the brown sugar liberally over the top of the buttered casserole. You may need more brown sugar depending on the dimensions of your casserole dish (and personal sugary preference!)
Broil the squash dish for about 3-5 minutes until the butter has melted and the surface begins to bubble and brown. The top should set to be slightly crunchy, like the surface of a good crème brûlée. Serve immediately.