Start by carefully slicing the spaghetti squash in half lengthwise. Scoop out the seeds using a spoon and discard them. Drizzle olive oil over the cut sides and season with salt and pepper for flavor.
Place the squash halves cut-side down in the air fryer basket. Cook at around 375°F (190°C) until the flesh becomes tender and easily pierced with a fork. This step creates perfectly soft strands with slightly crisp edges.
Once cooked, let the squash cool slightly before handling. Use a fork to gently scrape the flesh into spaghetti-like strands. Keep the strands inside the shell to create a natural serving bowl.
Spoon marinara sauce evenly over the shredded squash strands. Sprinkle mozzarella and Parmesan cheese generously on top, ensuring full coverage for a cheesy finish.
Return the stuffed squash halves to the air fryer. Cook for a few more minutes until the cheese melts and becomes bubbly with a slightly golden top. This step brings everything together beautifully.
Remove from the air fryer and let cool slightly before serving. Top with fresh basil or extra Parmesan for added flavor and presentation.