Preheat the oven to 375 °F (190 °C). Line a rimmed baking sheet with parchment paper or a silicone baking mat.
Cut the squash in half down the center, vertically (makes longer spaghetti-like strands) or horizontally (makes shorter strands). Use your hands or a spoon to scoop out and discard the seeds.
Place the squash halves, cut side down, onto the baking sheet and bake for 40-50 minutes, until the squash is tender.
Carefully remove the sheet from the oven and, using tongs or oven mitts, transfer the squash to a plate to cool.
Once cool enough to handle (about 10 minutes), use a fork to rake the inside of the squash and place the spaghetti-like strands in a container. Make sure to scrape out all of the squash flesh from the skin, using a spoon at the end if necessary. Discard the skin.
Allow to cool completely, then store in a sealed container in your fridge.