Preheat your oven to 425°F. Line a baking sheet with parchment paper.
In a small bowl, whisk together the olive oil, garlic powder, onion powder, smoked paprika, salt, and black pepper.
Place the cabbage steaks on the prepared baking sheet. Brush both sides of each steak generously with the olive oil mixture.
Roast in the preheated oven for 25-30 minutes, flipping halfway through, until the edges are crispy and the cabbage is tender.
If desired, drizzle the balsamic vinegar over the cabbage steaks during the last 5 minutes of roasting for added flavor.
Remove from the oven and let cool slightly. Garnish with fresh parsley before serving.