Preheat your oven to 350°F (180°C) and line a baking sheet with parchment paper.
In a medium bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy.
Add the egg and vanilla extract, and mix until well combined.
In a separate bowl, whisk together the flour, cocoa powder, baking soda, salt, grapefruit zest, and ground star anise.
Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.
Using a cookie scoop or spoon, drop rounded tablespoons of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake the cookies for 10-12 minutes, or until set. Allow them to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.
Enjoy!
