Stir the condensed milk in a medium saucepan over a low heat with the milk and cocoa until smooth.
Add the milk powder and continue to stir over a low heat for about ten minutes until the mixture is cooked and comes together in a ball. Leave until cool enough to handle but still warm.
Take a teaspoonful of the mixture at a time and roll into balls between the palms of your hands - you should get 18 balls.
Place on a wire rack, cover with baking parchment and leave to cool completely.
Toast the hazelnuts by dry frying in a pan over a medium heat for about 8 minutes, shaking from time to time to ensure they don't burn.
Leave to cool, then finely chop with a knife and put into a small bowl.
Melt the chocolate buttons gently in a bowl suspended over a pan of hot water. Stir until smooth. Remove from the heat then add the chocolate hazelnut spread.
Dip the ladoos into the chocolate and remove with a fork. Tap the fork on the side of a bowl to remove as much of the surplus chocolate as possible.
Roll in the nuts, then place back on the rack to set.
You'll need to chop the hazelnuts quite finely or you may not have enough to coat all 18 of your ladoos.Please note: calories and other nutritional information are per serving. They're approximate and will depend on exact ingredients used.