Position a rack in the center of the oven; preheat to 350°. Grease six 1-cup ramekins with the softened butter and place on a large rimmed baking sheet.
In a large bowl, whisk the melted butter, milk, hazelnut spread, eggs and vanilla until smooth. In a small bowl, whisk the flour, 1/3 cup brown sugar, 3 tbsp. cocoa powder, the baking powder and salt. Whisk the flour mixture into the hazelnut mixture. Divide the batter among the ramekins, about 1/2 cup batter for each.
In a small bowl, stir the remaining 1/3 cup brown sugar, 1/3 cup cocoa powder andthe granulated sugar, breaking up any clumps of brown sugar. Sprinkle each ramekin with about 2 rounded tbsp. of the cocoa-powder mixture.
Gently pour 1/3 cup boiling water into each ramekin. Bake until the puddings bounce back whengently pressed, about 30 minutes. Let stand 10 minutes before serving. Dust with cocoa and top with the whipped cream and nuts.
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