Chop the nuts into pieces and dry in a dry frying pan.
In a small saucepan, mix condensed milk with cocoa. Pour sugar and nuts to the condensed milk, mix.
Cook the mixture over low heat for about 15 minutes, until it begins to lag behind the walls of the pan.
Line a small form with foil, grease with butter and pour hot chocolate mixture into it.
Cool the future toffees a little and put in the refrigerator for 3 hours. Remove the frozen briquette from the mold and remove the foil. Cut it into small toffee candies and serve.