Preheat the oven to 425°F. Line a rimmed baking sheet with foil or parchment paper, or spray it with nonstick spray.
Brush both sides of each cauliflower steak with the olive oil, and place them on the prepared baking sheet. Lightly salt the steaks. Toss the extra florets with some olive oil, sprinkle them with salt, and distribute them alongside the steaks. Roast for about 25 minutes, until the steaks are just tender, and browned in spots.