Beat sugars and butter together in a medium bowl with an electric mixer until creamy. Add egg, miso and vanilla and beat until well mixed.
Add flour and baking soda and mix until just combined. Stir in chocolate chips. Cover with plastic wrap and refrigerate at least 1 hour. Don't skip the dough chilling - this step is very important in order to have a chewy cookie!
Preheat oven to 350F degrees and put parchment paper on two baking sheets or grease with your favorite oil (I prefer grass-fed butter).
Use an ice cream scoop to portion cookie dough on the baking sheets and lightly flatten each scoop of dough.
Bake, rotating and switching the pans halfway through, 13 to 14 minutes for a chewy cookie (a few minutes longer if you like a more well-done cookie).
Eat warm or let cool on a wire rack.