To roast halves, slice vertically into two pieces. Scoop out seeds and discard. Rub olive oil or water onto cut edges and place cut-side down onto a rimmed baking sheet.
Roast for 45-60 minutes, until soft. Flip over and let cool until easily handled, then scoop out flesh and mash or puree.
For roasted butternut squash cubes
Peel squash and cut neck from bulbous end. Halve both ends, scoop out seeds and discard. Cut squash into 1-inch cubes.
Toss with olive oil and salt and pepper. Spread in an even layer on a rimmed baking sheet and roast for 30-45 minutes, until tender and edges are lightly caramelized.