Thick cabbage wedges roast at high heat until tender with browned edges, then get finished with a quick garlic butter and a squeeze of lemon so flavor seeps into every layer.
Preheat the oven to 400°F / 200°C. Place a large rimmed baking sheet on the middle rack while the oven heats, or line it with parchment for easier cleanup.
Remove any wilted outer leaves. Trim a thin slice from the base of the core so it’s clean but still intact. Cut the cabbage in half through the core, then cut each half into 3–4 thick wedges (about 1 1/2 inches / 4 cm thick). Keep the core attached so the wedges hold together.
In a small bowl, mix olive oil with 1/2 tsp salt, smoked paprika, garlic powder, black pepper, and red pepper flakes (if using). Arrange wedges on the baking sheet cut sides up and spoon or brush the seasoned oil over the wedges, working it into some of the layers.
Roast for 20 minutes, until edges are starting to brown (check at 15 minutes if your oven runs hot).
Flip each wedge with a spatula and tongs so another cut side faces up. Spoon any oil from the pan over the exposed surfaces. Roast 15–20 minutes more, until edges are well browned and a knife slides into the core with slight resistance.
While the cabbage finishes roasting, melt the butter in a small saucepan over low heat (or in a microwave-safe bowl). Stir in minced garlic, remaining 1/2 tsp salt, remaining smoked paprika, and a pinch of black pepper. Warm gently 1–2 minutes until fragrant; do not brown the garlic.
Remove the cabbage from the oven and drizzle or brush with the warm garlic butter, letting it seep into the layers. Squeeze lemon juice over the top. For a mellower garlic flavor and extra crisp edges, return the tray to the turned-off oven for 3–5 minutes.
Transfer wedges to a platter, spoon any remaining butter over the top, and sprinkle with parsley if using. Taste and adjust with an extra pinch of salt or more lemon as needed.