Wash the squash thoroughly, removing any traces of dirt or debris.Using a very sharp knife and a sturdy cutting board, slice off the ends of the squash.Slice the squash in half from the stem to the tip, then remove the seeds and membrane with a metal spoon.
Turn the halves flesh side down, then cut the squash crosswise into slices about ¾ inch thick.
In a small bowl, combine the olive oil, cinnamon, sea salt, and pepper.Preheat the air fryer to 390°F. for 3 minutes.
Using a paper liner or a silicone liner, arrange the squash slices in a single layer in the basket. Using a pastry brush, brush all over with the olive oil mixture.Air fry for 8 to 12 minutes, depending on the type of air fryer you have. Cook times vary between different models.
Once the slices are fork tender and golden brown, baste them lightly with maple syrup. Air fry for another minute or two.
Arrange on a serving dish. Taste and add a little more sea salt and pepper if you think it needs it. Serve hot. You can garnish the dish with fresh herbs like thyme or rosemary if you'd like.
Notes
Make sure to leave spaces between the slices so the hot air can circulate. If you crowd the air fryer basket, the squash will cook in its own steam and it won't develop a slightly crispy exterior. You may have to cook it in batches, depending on the size of your air fryer.