Prepare the Eggplant. Preheat oven to 400°F. Slice eggplants in half lengthwise. Score the flesh in a crisscross pattern without cutting through the skin. Brush lightly with sesame oil.
Roast Until Tender. Place eggplant halves on a parchment-lined baking sheet, cut side up. Roast for 20–25 minutes, until the flesh is soft and golden.
Make the Miso Glaze. In a small bowl, whisk together miso paste, soy sauce, rice vinegar, sesame oil, and honey (or maple syrup). Add garlic and ginger if using.
Glaze and Broil. Remove eggplants from the oven and brush generously with the miso glaze. Place under the broiler for 2–3 minutes until caramelized and slightly charred at the edges.
Garnish and Serve. Sprinkle with sesame seeds and scallions. Serve hot as a side dish, over rice, or as part of a veggie platter.