Preheat the air fryer to 400°F (200°C).
Place the sweet potatoes in a large pot and cover with water. Bring to a boil over high heat and cook until the sweet potatoes are tender when pierced with a fork, about 15-20 minutes.
Drain the sweet potatoes and let them cool slightly until they can be handled.
Place the sweet potatoes on a large cutting board or baking sheet. Using the bottom of a glass or a sturdy spatula, gently press down on each sweet potato to flatten it to about 1/2 inch thickness without breaking it apart.
Brush both sides of each smashed sweet potato with olive oil.
In a small bowl, mix together the garlic powder, smoked paprika, salt, and black pepper. Sprinkle the seasoning evenly over both sides of the sweet potatoes.
Arrange the smashed sweet potatoes in a single layer in the air fryer basket. You may need to cook them in batches depending on the size of your air fryer.
Air fry at 400°F (200°C) for 12-15 minutes, flipping halfway through, until the sweet potatoes are golden brown and crispy on the edges.
Remove from the air fryer and sprinkle with chopped fresh parsley before serving.