Preheat oven to 400 degrees. Slice off the top of the squash, and slice it down the middle. Lay it innards down on a baking sheet for about 30 minutes, or until a fork punctures it easily. Dice onions, slice mushrooms and sautee in butter until very soft, add garlic last. Set aside and let cool.
Separate yolks from the white and add the yolks to the cooled pan of onions, shrooms and garlic. After the squash has cooled, remove the seeds and scoops out all of the strands into the pan with the onions, garlic, yolks, etc. Let it reheat on low.
Cook the bacon until it is crispy and crumble over the squash. Truthfully, I also drizzled the bacon fat over the spaghetti.
Notes
Make sure to use pastured eggs for the best carbonara!