Triple Chocolate Cinnamon Rolls

Ingredients

For the Dough:

• 1 cup whole milk
• 1 1/4-ounce packet active dry yeast
• 1/4 cup plus 1/4 teaspoon granulated sugar
• 4 tablespoons unsalted butter, melted and cooled slightly, plus more for the bowl and dish
• 1 large egg yolk
• 2 teaspoons pure vanilla extract
• 2 3/4 cups all-purpose flour, plus more for dusting
• 2 tablespoons Dutch-process unsweetened cocoa powder
• 1 teaspoon kosher salt

For the Filling:

• 1/4 cup granulated sugar
• 2 teaspoons ground cinnamon
• 6 tablespoons unsalted butter, softened
• 2/3 cup chocolate-hazelnut spread (such as Nutella)
• 1/3 cup finely chopped hazelnuts

For the Glaze:

• 2 ounces semisweet chocolate, chopped, plus shaved chocolate for topping
• 1 1/2 cups confectioners’ sugar
• 5 tablespoons milk
• 2 tablespoons unsalted butter, melted
• 1 teaspoon pure vanilla extract
• Pinch of kosher salt

Description

1. Make the dough: Heat the milk in a small saucepan over low heat until it reaches 100 degrees F on a thermometer. Remove from the heat and sprinkle the yeast and 1/4 teaspoon granulated sugar on top (do not stir); set aside until foamy, 5 minutes.
2. Whisk the melted butter, egg yolk and vanilla into the yeast mixture. Add the flour, cocoa powder, remaining 1/4 cup granulated sugar and salt to the bowl of a stand mixer. Mix with the dough hook on medium speed to combine. Make a well in the center, add the milk mixture and beat on medium speed. Increase the speed to medium-high and continue beating until the dough is sticky and elastic, about 6 minutes. (Alternatively, stir the yeast mixture into the flour mixture in a bowl with a wooden spoon, then knead by hand.) Transfer the dough to a clean surface and form into a ball. Brush a clean bowl with melted butter. Add the dough and turn to coat in the butter; cover with a kitchen towel and set aside in a warm place until doubled in size, about 1 1/2 hours.
3. Make the filling: Butter a 9-by-13-inch baking dish. Stir together the granulated sugar and cinnamon in a small bowl. Turn out the dough onto a lightly floured surface and pat into a rectangle, then roll out into a 10-by-18-inch rectangle. Spread the softened butter over the dough, leaving a 1-inch border along one long side; sprinkle the cinnamon sugar over the top. Dollop teaspoons of the chocolate-hazelnut spread all over the dough, about 1 inch apart, then sprinkle the hazelnuts all over. Brush the unbuttered border with water. Starting from the opposite long side, tightly roll up the dough, shaping it with your hands into an even log (it will be 22 to 24 inches at this point). Pinch the seam to seal.
4. Trim the ends of the log, then cut it into 12 rounds, about 1 1/2 inches thick. Place cut-side up in the baking dish. Cover loosely with plastic wrap and set aside in a warm place until doubled in size, 1 to 1 1/2 hours.
5. Preheat the oven to 350 degrees F. Uncover the rolls. Bake until they spring back when gently pressed, 25 to 30 minutes. Let cool 15 minutes. Meanwhile, make the glaze: Put the chocolate in a microwave-safe bowl and microwave in 30-second intervals, stirring, until smooth. Let cool. Whisk together the confectioners’ sugar, milk, melted butter, melted chocolate, vanilla and salt in a medium bowl until smooth. Spoon and spread the glaze all over the rolls and sprinkle with shaved chocolate.