Rinse the spaghetti squash and thoroughly dry. On a cutting surface, use a large sharp knife to cut the squash in half lengthwise. Scrape out the seeds and discard. Brush olive oil onto the cut side. Place the squash, cut side down, on a foil- or parchment-lined baking sheet. Bake in a preheated 350-degree oven. Start checking for to see if it’s done after 20 minutes. The skin will be just turning light brown and it will give a little when you press your finger into it. When you pull your fork through the flesh, spaghetti-like strands should release. Be careful not to over-bake,– the squash will be mushy and won’t look like spaghetti.