Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.
In a mixing bowl, whisk together the flour, baking powder, baking soda, salt, and ground hibiscus petals until well combined. Set aside.
In another large bowl, beat the softened butter and granulated sugar together using an electric mixer until the mixture is light and fluffy, about 3-4 minutes.
Add the egg and vanilla extract to the butter mixture and continue mixing until fully combined.
Gradually add the dry flour mixture to the wet ingredients, mixing on low until just combined. Be careful not to over-mix the dough.
Scoop tablespoon-sized portions of dough and roll them into balls. Place them on the prepared baking sheets, spacing them about 2 inches apart.
Flatten each cookie ball slightly with the bottom of a glass, creating a smooth surface.
Bake in the preheated oven for 10-12 minutes or until the edges are lightly golden. The centers might still look soft – that's okay!
Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
Once cooled, dust the cookies lightly with powdered sugar for an elegant finish.