Preheat oven to 400 degrees and spray a baking sheet with nonstick cooking spray.
Pull outer leaves off cabbage, cut cabbage from top to bottom (bottom being root) into 1-inch thick slices.
Rub both sides of cabbage with smashed garlic.
Use a pastry brush to evenly spread the olive oil over both sides of the cabbage slices.
Finally sprinkle each side with a bit of kosher salt and freshly cracked black pepper.
Roast on the middle rack for 30 minutes.
Carefully flip the cabbage steaks and roast for an additional 30 minutes until edges are brown and crispy.