In a medium saucepan, melt the Nutella, butter, and chocolate chips over medium-low heat, stirring occasionally. Remove from the heat.
Place the Crispix in a large bowl and pour the melted chocolate mixture over the top. Gently stir well to coat evenly.
Combine the confectioners' sugar and cocoa in a sifter and sift over the nuggets. Toss to coat evenly. Store in an airtight container.
YIELD: About 12 cups of nuggets