Directions

• Process hazelnuts in a food processor until finely ground. Whisk flour, baking powder, salt, and hazelnut together in a medium bowl.
• Using the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium-high speed until pale and fluffy. Add the egg and yolk one at the time, the espresso powder, and vanilla, until combined.
• Reduce the speed to low and add the flour mixture in three times, until well incorporated. Divide the dough in two, form 5 inch disks, wrap in plastic wrap, and refrigerate for an hour.
• Preheat the oven to 375 degrees Fahrenheit. Line 2 baking sheets with parchment paper.
• Take the dough from the refrigerator and let it soften until ready to roll between plastic wrap, to 1/8 of an inch hight. Using a 2 1/4 inch round cookie cutter, cut out as many disks as possible and place them on the baking sheets, 1/2 inch a part from each other. You might need to use the baking sheets more than once.
• Bake until the edges are slightly brown, 7 to 8 minutes. Let them cool for 5 minutes onto the baking sheet, then transfer them on a cooling rack.
• While the cookies cool down. place the heavy cream in a microwave safe bowl and heat it up until it boils. Add the chocolate and let it sit for a couple of minutes. Use a whisk and mix the ganache until smooth.
• Spread the ganache on the bottom cookies, then place to top cookies, pressing slightly. Let it rest until firm.