Preheat the oven to 400°F.
Slice across a head of cabbage to create ½-inch thick rounds. Brush each side with olive oil.
Place on a rimmed baking sheet (cut rounds in half to fit on the pan if needed). Roast for 25 to 30 minutes. Broil for 1 to 2 minutes if desired.
Drizzle with butter and serve.
