Prep the oven & eggplant: Preheat oven to 400°F (200°C). Line a baking tray with parchment. Cut eggplants in half lengthwise and score the flesh in a crosshatch pattern without cutting through the skin.
Roast the eggplants: Lightly brush the eggplant flesh with oil and place cut-side up on the tray. Roast for 20 minutes until softened and lightly golden.
Make the miso glaze: In a bowl, whisk together miso paste, maple syrup, rice vinegar, soy sauce, sesame oil, ginger, and garlic until smooth.
Glaze and finish roasting: Remove eggplants from oven, brush generously with the miso glaze, and return to oven for 8–10 more minutes. Broil for the final 1–2 minutes for caramelization (watch closely!).
Garnish and serve: Sprinkle with sesame seeds and scallions. Serve hot as a side or over rice, noodles, or with a light salad.