Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a small saucepan, melt the unsalted butter over low heat. Once melted, remove from heat and whisk in the miso paste, maple syrup, minced garlic, and sesame oil until well blended.
In a large bowl, add the halved Brussels sprouts and pour the miso butter mixture over them. Toss gently to ensure all the Brussels sprouts are well-coated.
Spread the Brussels sprouts evenly on the prepared baking sheet, cut side down for maximum caramelization.
Roast in the preheated oven for about 20-25 minutes, or until the Brussels sprouts are tender and golden brown, shaking the pan halfway through to ensure even roasting.
Once done, remove the baking sheet from the oven and season with salt and pepper to taste.
Transfer the Brussels sprouts to a serving dish and sprinkle with sesame seeds and sliced green onions for garnish before serving.
Notes
Optional sesame seeds and green onions can enhance the presentation.