Trim brussels sprouts if needed and cut each one in half, length-wise.
Transfer brussels sprouts into a mixing bowl. Add olive oil, salt, dried parsley, and garlic powder.
Toss it all together until all the sprout halves are evenly coated with oil and seasoning.
Spread brussels sprouts on the baking sheet in one even layer. Don’t overcrowd them. Make sure that all the halves are turned cut side up to hold Parmesan cheese better.
Spread shaved Parmesan cheese evenly over all the halves. (You will want each bite to have cheese on top.)
Roast brussels sprouts at 425° for about 18 minutes. (Time will depend on the size of the sprouts so take away a couple of minutes for smaller ones or add a couple minutes for large ones.)