Preheat oven to 400°F and lightly coat a baking sheet with nonstick spray.
Slice cabbage into steaks: Trim bottom to create a flat edge, then slice from the top to bottom into 1-inch-thick pieces.
In a small bowl, whisk together olive oil, balsamic vinegar, honey, salt, and pepper. Brush onto both sides of cabbage steaks, and place steaks on baking sheet(s). Sprinkle with chile flakes, if desired.
Bake for 20-25 minutes, rotating pans halfway through. Serve immediately.