In a bowl, combine the flour, sugar, baking powder, salt and cardamom powder. Then add the butter and mix well so that it now resembles breadcrumbs.
Add the cardamom powder and milk, little at a time and knead into a dough. Divide into small equal portions. Give a round flat shape to each of them and make few slits with a knife.
Place a pinch of the sliced pista in the centre and arrange them in a greased idli stand. Place the salt in the bottom of a pressure cooker and place a stand over it.
Preheat the cooker on a medium flame for 10 minutes. Now gently place the idli stand in it and close with the lid, but without the vent.
Cook on a low flame for 10-15 minutes. Keep checking for doneness. Switch off the flame and let it remain as it is for another 5 minutes.
Brush with some melted butter / ghee and cool them on a wire rack. Store in an airtight container. Serve as a tea-time snack or as and when desired.