To make the cookies:

• Whisk together flours, cocoa powder, cornstarch, baking soda and salt in a medium sized bowl.
• In a bowl of a stand mixer cream together the butter and sugars until light and fluffy, 6-7 minutes. Add in the whole egg and egg yolk and mix again, scraping down the sides of the bowl when needed, then add in the vanilla and mix for another minute. Add in the flour mixture and mix on low until combined and no flour streaks remain then mix in the chopped chocolate and passionfruit feves by hand so they don’t break. 
• Transfer the dough to another bowl and wrap well with plastic wrap. I will press the plastic wrap agains the dough then place another over the top of the bowl. Refrigerate the dough for 24 hours. 
• When ready to bake heat oven to 350 Deg F and prepare baking sheets with parchment paper. 
• Using a 2 tablespoon sized cookie scoop, scoop out generous balls of dough, placing a few inches apart on the prepared baking sheets. Press down lightly and press a passionfruit feve into the tops of each one. Sprinkle some of the hibiscus salt across the tops of the cookies
• Bake for 10-12 minutes or until the cookies are set. Remove from oven and sprinkle a little more salt over the tops, let cool on baking sheet for 5 minutes, then transfer to a wire cooling rack to cool completely. 
• These keep well at room temperature in an airtight container or resealable bag for a week or so, a few months in the freezer. That is if you don’t eat them all in a few days.