Heat oven to 450 degrees. Line a baking sheet with parchment or silicone.
Cut cabbage half into four equal wedges and set on prepared baking sheet. Use a pastry brush to coat the cut side of each wedge with oil and sprinkle with salt and pepper. Turn wedges and repeat.
Place the baking sheet in the oven and cook for 10-12 minutes. Flip the wedges and roast until nicely browned, 8-10 minutes more.
Meanwhile, make the sauce by adding all the sauce ingredients to a small saucepan and cook over medium heat until the butter is completely melted. Keep warm (alternately, place ingredients in a microwavable container and cook on high for about 1 minute - warm again before using).
To serve, place the wedges on a plate, whisk sauce again* and drizzle over wedges. Sprinkle with chives or parsley, if desired.
*The sauce may separate, so whisking right before topping the cabbage will emulsify it again.