Preheat the oven to 350° F. Arrange Butternut Squash cubes on a large rimmed baking sheet and toss with oil. Season with salt and pepper. Roast for 30 minutes or until tender. Let cool slightly.
Increase the oven temperature to 375° F. Spread corn bread cubes on a large baking sheet and bake for about 20 minutes, until toasted. Let cool completely. Leave oven on.
Generously butter a 12 cup muffin tin. In a medium skillet, cook the bacon over moderate heat until crisp. Using a slotted spoon, transfer bacon to a paper towel–lined plate. Heat ¼ cup of bacon fat in the skillet. Add red onion and cook over moderate heat until softened, about 4 minutes. Add celery, garlic, sage and cook, stirring occasionally, until the celery is softened, about 4 minutes. Stir in the bacon.
Transfer the squash to a large mixing bowl. Add the toasted corn bread. Season the mixture with salt. Add sugar and eggs and toss until coated thoroughly. Add the chicken stock and toss again thoroughly. Add the onion-bacon mixture and stir again. Let stand for 5 minutes.
Mound the stuffing in the prepared muffin cups. Wrap any extra stuffing in a piece of heavy-duty foil.