• Gather all the ingredients. Set the rack in the center of the oven about 7 inches (18 cm) away from the heating element. Preheat the oven to 425ºF (220ºC). For convection, reduce the temperature by 25ºF (15ºC).
  

To Make the Sweet Miso Glaze

• Combine 3 Tbsp miso and 1 Tbsp sugar in a small bowl. Mix well to dissolve the sugar.
  
• Add 1 Tbsp mirin and ½ Tbsp sake and stir. If needed, you can add a bit more sake until you reach your preferred consistency, as some miso is chunkier than others. Mix well and set aside.
  

To Prepare the Eggplants

• Cut off the stem and calyx of 3 Japanese eggplants. Cut the eggplants in half lengthwise from stem to tip, creating boat-like halves. If your eggplants are long, you can cut them in half crosswise so they're shorter.
  
• With the knife, score the cut surface of eggplant diagonally about ⅛ inch (3 mm) deep and apart. Work in one direction first and then the other, creating a crisscross pattern on the flesh. Tip: In addition to improving the presentation, this crisscross scoring helps the eggplants cook faster and absorb more flavor.
  
• Soak them in water for 10 minutes to remove the astringency. Blot them with paper towels or a clean kitchen towel and place on a baking sheet lined with parchment paper.
  
• Brush the cut surface with 1 Tbsp toasted sesame oil. Turn them over so they are cut side down on the baking sheet.
  

To Bake

• Bake the eggplants at 425ºF (220ºC) for 15 minutes.
  
• Meanwhile, cut 1 green onion/scallion into thin rounds. Roll up 5 shiso leaves (perilla/ooba) and cut them into julienned strips.
  
• After 15 minutes, the eggplant flesh should be soft and the skin slightly shriveled. Remove the baking sheet from the oven. Now, preheat the broiler. Keep the rack in the same center position, roughly 7 inches (18 cm) away from the heating element.
  

To Broil

• Carefully turn the eggplants cut side up and brush the flesh with a layer of sweet miso glaze. Coat the surface completely. You don't need to use all the glaze; one batch makes enough for 3 large or 5 medium eggplants. Tip: You can freeze any leftover glaze to use later or enjoy it as a dip for veggies.
  
• Place the eggplants under the broiler until the glaze begins to bubble and caramelize, about 3–5 minutes. Remove from the broiler. Tip: The cooking time varies based on how far away you place the food from the heating element.
  

To Serve

• Sprinkle the baked eggplants with 2 tsp toasted white sesame seeds, sliced green onions, and julienned shiso leaves. I serve a dab of yuzu kosho (optional) on a maple leaf for a spicy kick. Serve immediately.
  

To Store

• You can keep the nasu dengaku leftovers in an airtight container and store it in the refrigerator for 3 days. You can keep the miso glaze leftovers in the fridge for up to 7 days or in the freezer for up to 1 month.