01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - Whisk together flour, baking soda, baking powder, and salt in a medium bowl. Set aside.
03 - Beat butter, miso, brown sugar, and granulated sugar in a large bowl until creamy and smooth, about 2-3 minutes.
04 - Add eggs one at a time, beating well after each addition. Mix in vanilla extract.
05 - Gradually add dry ingredients to wet mixture, mixing just until combined.
06 - Fold in chocolate chips or chopped chocolate.
07 - Scoop dough (about 2 tablespoons per cookie) onto prepared baking sheets, spacing about 2 inches apart.
08 - Sprinkle with flaky sea salt if desired.
09 - Bake for 11-13 minutes, until edges are golden and centers are still slightly soft.
10 - Cool on baking sheet for 5 minutes, then transfer to wire rack to cool completely.