Melt butter in a pan over low heat.
Add milk and bring to a gentle simmer.
Turn off the heat and quickly stir in milk powder until smooth and thick.
Add icing sugar, vanilla essence, and cardamom. Mix well until the mixture comes together and pulls away from the sides.
Pour into a lined square tray and smooth the top.
Sprinkle coconut and nuts on top, pressing lightly.
Allow to cool completely, then refrigerate for 2–3 hours until firm.
Cut into small squares and serve.