Preheat the oven to 400°F. Line a rimmed baking sheet with foil and generously spray it with olive oil.
Remove the cabbage’s damaged outer leaves. Cut it in half and then into wedges. Leave the core in - there's no need to cut it out. If you do, the wedges will fall apart.
Rinse the cabbage wedges, then carefully dry them using paper towels. Place the wedges in a single layer on the prepared baking sheet.
Generously spray the cabbage with olive oil. Season it with kosher salt, garlic powder, and red pepper flakes.
Roast the cabbage until golden brown and fork-tender, 25-30 minutes. Serve immediately.
Video
Notes
Note that when you lift the baked cabbage slices from the pan, they will somewhat fall apart on you. That's totally expected, so don't let that distress you. They will, for the most part, keep their pretty shape.
I like this dish spicy, so I use quite a bit of red pepper flakes. But I wrote this recipe keeping in mind that not everyone likes their food spicy. In any event, you can simply omit the red pepper if you wish.
You can keep the leftovers in an airtight container in the fridge for up to 4 days. Reheat them in the microwave at 50% power. They are also good when served cold! Sometimes, I shred them and add them cold to a salad the next day. I also like to snack on them cold - just like antipasti.