Melt 1 tablespoon of butter and prepare a sheet of aluminum foil by brushing one side with melted butter and set aside.
In a small saucepan add the remaining butter and sugar and 2-3 tablespoons water. Heat over medium heat and stir while sugar melts. Increase heat, bring to a boil and cook until golden brown, about 5-10 minutes. Remove from heat, stir in Hawaii macadamia nuts, and spread mixture out onto prepared aluminum foil. Set aside to cool. Once cool, break into pieces.
In a medium saucepan add milk and chocolate. Heat over medium low, stirring while chocolate melts. Using a hand blender or frother, briefly blend once melted.
Pour hot chocolate into cups and add pieces of brittle for serving.
