Beat the softened butter and icing sugar in a large bowl until fluffy.
Stir in the wholewheat flour, milk powder and cardamom powder with a wooden spoon. Use your hands to bring this together to form a dough. Divide into 2 halves. Cover the dough halves in plastic wrap or aluminium foil. Refrigerate for 30 minutes.
Preheat the oven to 170C. Cover your baking tray with silpat or parchment paper.
Working with one dough half at a time, roll out the dough to about 1/2" thickness. Using a cookie cutter, cut out the cookies. Use a fork to prick some design on top. Sprinkle some crushed pistachio on top ( optional).
Bake for 10-12 minutes or until the cookies are light golden brown. Cool on a cooling rack. The cookies will get crisper as they cool.
The cookies I made, were done in 12 minutes. As your oven temperature maybe different, do keep an eye on the cookies so they don't get overdone or stay undercooked.