Directions
<ol class="no-list-style"><li class="MethodStepper"><h4 class="step-title">Step 1</h4>Place the ground hazelnuts in a dry skillet over medium heat and toast for 3-4 minutes, stirring frequently, until they become fragrant and slightly darker in color. This toasting step intensifies the nutty flavor that makes these cookies special. Allow to cool completely before proceeding.</li><li class="MethodStepper"><h4 class="step-title">Step 2</h4>In a large bowl, cream together the softened butter and sugar until pale and fluffy, about 3-4 minutes. The mixture should lighten in color significantly - this incorporates air into the dough, creating the delicate texture typical of Austrian cookies.</li><li class="MethodStepper"><h4 class="step-title">Step 3</h4>Add the egg yolks one at a time, beating well after each addition. Mix in the vanilla extract and lemon zest. The lemon zest provides a subtle brightness that balances the rich nuts and chocolate.</li><li class="MethodStepper"><h4 class="step-title">Step 4</h4>In a separate bowl, whisk together the flour, cooled toasted ground hazelnuts, and salt. Gradually add this dry mixture to the butter mixture, mixing on low speed just until combined. Overmixing will develop the gluten in the flour and make your cookies tough rather than tender.</li><li class="MethodStepper"><h4 class="step-title">Step 5</h4>Divide the dough into two equal portions, flatten each into a disk, wrap in plastic wrap, and refrigerate for at least 2 hours or overnight. This chilling time is crucial as it firms the butter, making the dough easier to roll and ensuring the cookies maintain their shape while baking.</li><li class="MethodStepper"><h4 class="step-title">Step 6</h4>When ready to bake, preheat your oven to 160°C (fan)/180°C (conventional) and line baking sheets with silicone mats or parchment paper. Remove one disk of dough from the refrigerator and let it sit at room temperature for about 10 minutes to slightly soften.</li><li class="MethodStepper"><h4 class="step-title">Step 7</h4>On a lightly floured surface, roll the dough to approximately 3mm thickness. Using a 5cm round cookie cutter, cut out circles and transfer them carefully to the prepared baking sheets, leaving about 2cm between cookies. Gather scraps, re-roll once, and cut more cookies.</li><li class="MethodStepper"><h4 class="step-title">Step 8</h4>Repeat the process with the second disk of dough, but after cutting the 5cm circles, use a 2cm round cutter to cut out the centers of half of these cookies. These will form the tops of your sandwich cookies, allowing the filling to peek through.</li><li class="MethodStepper"><h4 class="step-title">Step 9</h4>Bake the cookies for 10-12 minutes until the edges are just beginning to turn golden. The cookies should not brown too much - they're meant to be pale with a delicate texture. Cool on the baking sheets for 5 minutes before transferring to wire racks to cool completely.</li><li class="MethodStepper"><h4 class="step-title">Step 10</h4>While the cookies cool, prepare the filling. In a heatproof bowl set over a pan of barely simmering water (ensuring the bottom doesn't touch the water), combine the chopped dark chocolate, chocolate-hazelnut spread, and butter. Stir occasionally until completely melted and smooth. Remove from heat and let cool until slightly thickened but still spreadable.</li><li class="MethodStepper"><h4 class="step-title">Step 11</h4>Dust the cookies with the cut-out centers (the tops) generously with powdered sugar. For the solid cookies (the bottoms), spread or pipe about 1 teaspoon of the chocolate filling onto the flat side.</li><li class="MethodStepper"><h4 class="step-title">Step 12</h4>Carefully place the powdered sugar-dusted tops onto the chocolate-covered bottoms, pressing very gently to sandwich them together. The chocolate filling should be visible through the cut-out center.</li><li class="MethodStepper"><h4 class="step-title">Step 13</h4>Allow the assembled cookies to rest for at least 1 hour for the filling to set. This patience will be rewarded with perfectly textured cookies where the filling has slightly softened the cookie bases while maintaining their structure.</li><li class="MethodStepper"><h4 class="step-title">Step 14</h4>Store in an airtight container with parchment paper between layers for up to 1 week. The flavor actually improves after a day as the cookies soften slightly and the flavors meld together. You can also freeze them for up to 3 months if you'd like to prepare them in advance.</li></ol>