Not only healthy but delicious and a great accompaniment for a main meal or for your holiday table. I also love eating this on it's own as a light lunch in which case I sometimes omit the butter (good without it too).
Grease a roasting pan or cookie sheet (with rims) with oil spray or olive oil.
Cut top and bottom end from butternut squash. Place flat end (that you've cut) of squash on cutting board and cut in half top to bottom.
With a spoon, scrape seeds out as well as webby silk, making sure that inside of squash is clean and void of all seeds and silk. Cut the squash in half-moon slices about 1" wide, keeping cut slices to the same thickness.
Place squash on roasting pan on their sides (pulp side down). Spacing slices evenly.
Mix together Agave nectar, balsamic vinegar and melted butter. Brush buttercup slices evenly. Note that only about half or less of the amount will be used. Reserve remaining balsamic/agave nectar.
Roast squash for approximately 15 minutes. Turn slices over to opposite side. Brush with remaining balsamic agave nectar. Roast 15 - 20 minutes more or until squash pierces easily with fork and is cooked through.
Season with ground black pepper and sea salt to taste. Serve while hot.