Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
Remove the leaves from the cauliflower and trim the stem, keeping the head intact.
Slice the cauliflower head into 3/4-inch thick steaks, yielding about 4-6 steaks.
In a small bowl, whisk together the olive oil, garlic powder, smoked paprika, salt, and black pepper.
Brush both sides of each cauliflower steak with the olive oil mixture.
Place the cauliflower steaks on the prepared baking sheet and sprinkle with Parmesan cheese if using.
Bake for 25-30 minutes, flipping halfway through, until golden brown and crispy.
Remove from the oven and garnish with fresh parsley before serving.