Preheat the oven to 425°F (220°C).

Carefully slice the cabbage into 1-inch (2.5 cm) thick rounds, keeping the core intact so the steaks hold together.

Brush both sides of each cabbage steak with olive oil.

Season evenly with sea salt and black pepper.

In a small bowl, mix together the softened unsalted butter, minced garlic, fresh thyme leaves, and fresh lemon juice until well combined.

Spread a generous amount of the garlic butter mixture over the top of each cabbage steak.

Arrange the cabbage steaks on a parchment-lined baking sheet, leaving space between each piece.

Roast for 20–25 minutes, flipping once halfway through, until the edges are deep golden and slightly crisp.

Remove from the oven and drizzle any remaining pan juices over the steaks.

Sprinkle with red pepper flakes, Parmesan cheese (if using), and fresh parsley.

Let rest for 3 minutes before serving.