Preheat the oven to 350F/180 C. Prepare a 8x8 inch square baking pan with parchment paper.
In a small pot, melt the butter and miso paste over medium heat until very hot and melted.
¾ cup unsalted butter, 1 tablespoon white miso paste
In a large bowl, add the sugar and chocolate chips. Pour the hot melted butter into the bowl and let sit 1 minute.
1 ¼ cup white granulated sugar, 1 cup semi-sweet chocolate chips
After 1 minute, start whisking together the sugar, butter, and chocolate until the chocolate is melted and everything is combined.
Whisk in the eggs one at a time until combined into the batter. When all of the eggs are combined, continue whisking for 1 minute.
3 large eggs
Add in the flour, baking powder, salt, and black cocoa powder. Fold them into the batter with a rubber spatula until just combined.
¾ cup all-purpose flour, ⅓ cup black cocoa powder, ½ teaspoon baking powder, ½ teaspoon salt
Pour the batter into the prepared baking pan.
Bake for 30-33 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs on it. If it's covered in wet batter, give them a few more minutes but keep an eye on them so they don't over-bake.
Let the brownies cool on a wire cooling rack until completely cool before cutting.
Optional (drizzle with miso glaze): Whisk together the milk, white miso paste, and powdered sugar together until smooth.
2 teaspoon white miso paste, 1 tablespoon milk, ¾ cup powdered sugar
Drizzle the cooled brownies with the miso glaze if desired.