Addictive chocolate-hazelnut spread stars in our two-tone version of chocolate bark. Making bark is easy–just melt chocolate, spread it out, and add your favorite toppings. We added one important step, though: tempering the chocolate (carefully melting and cooling it to specific temperatures while adding large chunks of unmelted chocolate) so the bark stays shiny and snappy. The temperatures for dark chocolate and white chocolate are a bit different, so follow directions carefully for best results. For other flavor options, try Dark Chocolate Peppermint Bark or White Chocolate, Pistachio, and Apricot Bark.
Line a large rimmed baking sheet with parchment paper.
Put chopped dark chocolate in a shallow, medium heatproof bowl. In a medium saucepan, bring 1/2 in. water to a bare simmer. Set bowl over pan and heat chocolate, stirring often, until melted and registers about 115° on a digital or instant-read thermometer, 3 to 7 minutes.
Remove bowl from water and dry underside. Let chocolate cool (at first, it will rise about 5°), stirring constantly, to 95°, 5 to 12 minutes. Add large dark chocolate pieces and stir constantly until chocolate cools to 88° to 90°, 2 to 3 minutes. Spoon out unmelted dark chocolate and save for other uses.
Pour melted dark chocolate onto center of parchment and spread with an offset spatula or flexible scraper to about 1 in. from pan edges. Let cool at least 30 minutes.
Microwave Nutella in a 1-cup glass measuring cup until 95° to 100°, 30 seconds. Stir, then cover tightly with plastic wrap and set on a folded towel to keep warm; set aside.
Put chopped white chocolate in a clean, shallow, medium heatproof bowl. Return water in saucepan to a bare simmer. Set bowl over pan and heat chocolate, stirring often, until melted and registers about 110° on a digital or instant-read thermometer, 3 to 4 minutes.
Remove bowl from water and dry underside. Let chocolate cool (at first, it will rise about 5°), stirring constantly, to 95°, 5 to 12 minutes. Add large white chocolate pieces and stir constantly until chocolate cools to 86° to 88°, 2 to 3 minutes. Spoon out unmelted white chocolate and save for other uses. Stir Nutella into melted chocolate, then spread over dark chocolate. Sprinkle with hazelnuts.
Set pan on a cooling rack and let stand at room temperature until chocolate is firm, about 7 hours. Cut or break bark into pieces.
Make ahead: Up to 1 month, airtight at room temperature.
Servings 0
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.