Preheat the oven to 425°F.

Spray a baking sheet with nonstick cooking spray. Remove outer leaves from the cabbage and discard. Slice the stem (also called the core) from the cabbage and discard. Place cut-side down on the cutting board, then cut into 1-inch slices.

Lay the cabbage slices on the baking sheet, then drizzle with the olive oil and sprinkle with the garlic salt, onion powder, salt, and pepper. Gently turn to coat both sides of cabbage with oil and spices. Spread slices out into a single layer.

Transfer baking sheet to oven and bake 30-35 minutes, until cabbage is tender and slightly charred.

Check to see that the cabbage is done. Remove from oven or add time as needed.

Serve immediately.