Butternut squash puree: cut the squash in two and scoop out the seeds. Place the squash halves face down on a microwave-safe dish. Cook 10 minutes, then see if ready. If still too hard, continue to cook another 5 to 10 minutes. Once thoroughly cooked, let cool, then scrape the flesh out with a spoon.
In the slow cooker receptacle, combine all the ingredients, including seasoning. Cook on low for approximately 90 minutes, or until pasta is cooked.
Toppings: combine all the ingredients in a bowl, then sprinkle over the mac and cheese. Serve immediately.