Preheat the oven to 400°F.
Cut the spaghetti squash in half lengthwise and scoop out the seeds.
Brush the insides with olive oil and sprinkle with salt and pepper.
Place the squash cut-side down on a baking sheet and roast for 30-40 minutes, until tender.
In a large bowl, combine the chopped spinach, artichoke hearts, cream cheese, sour cream, mozzarella cheese, Parmesan cheese, garlic powder, onion powder, and red pepper flakes. Mix until well combined.
Once the squash is cooked, let it cool for a few minutes. Use a fork to scrape the flesh into spaghetti-like strands, leaving a small border around the edges.
Mix the strands with the filling mixture until well combined. Spoon the mixture back into the squash halves.
Return the stuffed squash to the oven and bake for an additional 15-20 minutes, until the filling is heated through and the top is slightly golden.
Let it cool for a few minutes before serving.