If you have a nut grinder, grind the 130g of hazelnuts to a flour-like consistency. My grinder tends to “eat” about 5g-10g of hazelnuts. You need a total of 125g of ground hazelnut “flour”.

Preheat your oven to 190°C/375°F.

In a bowl, combine 125g of butter, 150g of sugar, and 125g of nut flour. Mix the ingredients together.

Add the 2 egg yolks to the mixture and thoroughly combine everything.

Gradually add 180g of flour to the bowl and mix until a shaggy dough forms. Ensure there are no dry spots in the dough.

Transfer the dough onto a countertop and knead it together until it becomes smooth and there are no dry spots. If you're using a stand mixer, you can skip this step and use a paddle attachment on a slow speed until the dough comes together.

Divide the dough into two equal halves and roll each piece into a log about an inch thick. Cut the logs into equal-sized pieces. While it's not necessary, you can weigh each piece to ensure they're the same size. Roll each piece into a ball.

Prepare a sheet tray lined with parchment paper. Take the reserved hazelnuts and the 2 egg whites. Place the cookie balls on the tray, leaving a little space between them as they don't spread much during baking. Dip a hazelnut in the egg white and press it into the center of each cookie ball. The egg white helps the hazelnut adhere to the cookie.

Bake the cookies in the preheated oven at 190°C/375°F until they turn golden brown.

Let cool then eat and enjoy!