In a medium bowl, whisk together the flour, baking powder, and salt until well combined.

In a large bowl, cream together the butter and sugar until light and fluffy. Add the egg and red bean paste, mixing until smooth.

Gradually add the dry ingredients to the wet mixture, folding gently until just combined.

Cover the dough and refrigerate for at least 4 hours, or overnight if preferred.

Preheat the oven to 325°F (160°C) and roll chilled dough into balls, coating them first in granulated sugar and then icing sugar.

Place cookie balls on a baking sheet, bake for 8-10 minutes until edges are set while centers remain soft.

Allow cookies to cool on the baking sheet for about 5 minutes before transferring to a wire rack.