Preheat oven to 400°F. Liberally spray a large baking sheet with cooking spray or brush with oil.
Trim stem of cabbage to level. Cut cabbage into 1 inch slices from top to bottom, around the core, leaving internal core intact. (You can cut out the core but, it helps the leaves stay together while slicing.)
In a small bowl mix together oil, salt, pepper, red pepper flakes, parsley and garlic. Mix well.
Brush liberally on all sides of cabbage steaks. Sprinkle tops with grated Parmesan cheese.
Bake for 20 minutes, rotate pan. Continue to roast another 15-20 minutes until golden, lightly charred and fork tender. You can broil for a few minutes to char further, if desired.