Spaghetti Squash Casserole with Caramelized Onions

1 large spaghetti squash
2 tablespoons olive oil
1 large yellow or white onion, sliced
1 cup shredded Asiago cheese
Salt & pepper

1. Heat oven to 400°F. Spray a 1 qt casserole dish or pie pan with cooking spray.
2. Cut the squash in half lengthwise and scoop out the seeds. Place the halves on a rimmed pan and drizzle them with a little olive oil. Sprinkle with salt and pepper and turn so they are cut side down. Roast for 45 minutes to 1 hour until fork tender and you can easily scoop out the strands. Place the scooped out squash in a bowl and let cool.
3. While the squash is roasting, heat 1 tablespoon of olive oil in a large cast iron pan or heavy skillet over medium heat. Add the onions and stir occasionally with a metal spatula, for 20-30 minutes, until onions are deep brown and caramelized. After the first 10 minutes, sprinkle onion with salt. If the onions start to brown too quickly, turn down the heat. Remove from pan and add to the squash. Let cool a few minutes.
4. Stir 1 cup of cheese into the squash onion mixture along with a dash of salt and pepper. Spread in the prepared dish. Sprinkle remaining cheese on top. Reduce oven temp to 350°F and bake squash for about 25-30 minutes. If you want to brown the cheese a bit, turn on the broiler for a few minutes. Be careful not to burn.