Break the cauliflower into florets, place florets into a colander, and rinse under cold running water. Drain florets and loosely pat them with a clean cloth or paper towel to remove excess water.
Place cauliflower in a food processor with the onion and process until crumbly. You can also use a box grater to grate the cauliflower.
Scoop cauliflower mixture into a bowl, and add chickpea flour, arrowroot, nutritional yeast flakes, paprika, garlic powder, and salt. Mix the mixture together as you would do with a batter. Make sure that your batter holds together, add more chickpea flour as needed.
Divide mixture into 6-8 equal portions. Shape mixture into flat rectangular disks with about 1/2 inch thickness.
Brush or spray the basket with oil to prevent sticking, Place 3-4 at a time in your air fryer basket. Cook at 375 F° for 20-25 minutes, turning halfway. The time it takes to cook your hash browns depends on your air fryer. Mine took 25 minutes.