For the bacon jus:

1. Heat a pot over medium-low heat. Add the oil and onion and cook until the onions begin to turn translucent. Add the bacon and continue to cook until the bacon becomes aromatic and the fat renders. Cover the bacon and onion with water, cover the pan, and simmer for two hours. Pour the mixture through a cheesecloth-lined strainer, reserving the liquid. Freeze overnight.

For the delicata squash:

1. Preheat the oven to 450°F. Cut the squash in half, remove the seeds, and reserve. Cut one half of the squash in half again, and then quarter. Cut the other half into thin strips. Place the squash on a lined sheet tray and rub the butter onto the squash. Sprinkle the brown sugar over the squash and season with salt and pepper. Roast for 20 to 25 minutes, removing the thin slices after they are crispy and golden. Continue roasting for an additional 10 to 15 minutes until the larger pieces are fork tender. While the squash is roasting, clean the seeds of any fibers, and season with salt, pepper, and additional olive oil. Place seeds on the sheet tray during the last five minutes of the roasting period, and cook until the seeds are golden and crispy.

For the buckwheat:

1. In a small sauce pot, combine the buckwheat groats with 2 cups water. Season with salt. Bring to a boil, cover, and reduce to a simmer. Cook for 10 to 12 minutes, until the water has reduced and the buckwheat groats are tender.

To serve:

1. Remove the bacon jus from the freezer and use a sharp knife to cut the white fat layer off. Discard. Place the remaining brown layer into a small saucepan and cook over medium until jus is melted and warm. Lightly season arugula with olive oil, salt and pepper. Plate the buckwheat, delicata squash pieces and slices, and squash seeds. Garnish with the arugula salad and bacon jus.