Preheat your oven to 425 degrees Fahrenheit. Line a rimmed baking sheet with parchment paper.
Remove your cauliflower from the package and cut off as much of the stem as possible. Make sure to still leave the inner stem in tact with all cauliflower pieces still attached.
Put the cauliflower stem side down on your cutting board. Start slicing your cauliflower into 1 inch steaks. Some of the cauliflower will crumble apart when you do this and some will stay fully attached together. Place all slices and pieces of cauliflower onto your prepared baking sheet.
Carefully drizzle 2-3 tablespoons of olive oil over your cauliflower. Use a brush or your fingers to rub the olive oil all over each cauliflower steak.
Now sprinkle salt and garlic powder (to taste) on your cauliflower. Only season one side. Seasoning both sides will make the cauliflower too salty.
Place your sheet of cauliflower steaks into your preheated oven on the middle rack and roast for 15 minutes.
After 15 minutes, remove from oven and carefully flip all pieces over. Return to oven and roast for an additional 15 minutes.
Remove from oven and sprinkle with the 3/4 cup shredded parmesan cheese and the 1/2 cup chopped fresh parsley.
Return to oven for 1 minute to let the cheese melt. Remove from oven and enjoy!
See photos above for cauliflower slicing technique.