Preheat your air fryer to 375°F. This usually takes about 3-5 minutes.
Start by peeling the butternut squash with a vegetable peeler, then cut it into 1-inch cubes. Make sure to remove the seeds and fibrous parts from the center.
In a large bowl, toss the butternut squash cubes with avocado oil, cinnamon, black pepper and any optional seasonings you prefer, such as paprika or garlic powder. Make sure the squash is evenly coated with the oil and seasonings.
Place the seasoned butternut squash cubes in the air fryer basket. Ensure they are in a single layer for even cooking. You may need to do this in batches if your air fryer is small.
Cook the butternut squash for about 12 minutes, shaking the basket or tossing the squash cubes halfway through the cooking time. Cooking times may vary depending on your specific air fryer, so check for doneness by piercing a piece with a fork. The squash should be tender and have a slightly crispy exterior.