Start by rinsing and removing the top layers of your leaves if they are dried or yellow. If your Brussels sprouts have a bottom stem, cut those off as well.
Pat them dry with a paper towel to remove all the excess moisture. Then cut each of the Brussels sprouts in quarters.
Next, toss the halved Brussels sprouts into a medium bowl and add in the oil and all the seasonings. Stir together until mixed well.
Place your Brussels sprouts in a single layer in the air fryer basket or tray and set your cook time for 8-10 minutes. Half way through the cook time, remove the basket and give it a good shake to turn the sprouts. This way no one spot will over crisp or burn.
Heat the air frier to 350 degrees F. and place your tray full of Brussel Sprouts inside.
Check that the outside crispiness is to your liking. If you want them a little crisper, add another 1-2 extra minutes.
The Brussels sprouts will shrink as they cook. Give them another good shake in the basket to mix them up and then gather them off to one side of the basket, still keeping them in pretty much in a single layer.
Remove from air Frier and sprinkle with grated Parmesan cheese and serve.