Step 1Add the butter to a saucepan over medium heat. Melt down and heat until browned. *See my post all about how to brown butter for more detail.
Step 2Pour the brown butter into a measuring glass and add the miso paste. Whisk to combine and set aside.
Step 3Preheat the oven to 350F (SEE NOTES) and line a large baking sheet with parchment paper.
Step 4In a medium mixing bowl, whisk together the flour, baking powder, baking soda, and salt and set aside.
Step 5In a large mixing bowl, add the sugar, dark brown sugar, and cooled miso brown butter. Whisk to combine.
Step 6Add in the egg and vanilla and whisk vigorously until the mixture turns pale and creamy.
Step 7Pour in the dry ingredients and use a rubber spatula to fold the two together. Right before the dry ingredients are fully mixed in, add in the chopped chocolate and fold to fully combine.
Step 8Use a large 2 oz scoop or 1/4 measuring cup and scoop out the cookies.
Step 9Add the sesame seeds to a small dish. Then press the tops of the cookie dough balls into the sesame seeds so they cover the very tops of each cookie.
Step 10Place 4 cookies on the baking sheet spaced a few inches apart. Bake for 11-13 minutes, or until the edges are a light golden brown and the centers look barely underdone.
Step 11Allow the cookies to rest on the baking sheet for about 5 minutes, then transfer to a cooling rack and bake the remaining cookies.
Step 12Let the cookies cool for about 20-30 minutes, then dig in! Enjoy!