Step 1: The cookies

In a bowl, mix the butter with the powdered sugar and the egg until you get a creamy and smooth texture.

Add the flour, cocoa, and ground hazelnuts. Continue mixing, but be careful not to overwork the dough.

Wrap the dough in plastic wrap and place it in the fridge for 1 hour.

Step 2: Baking

Preheat the oven to 350°F (180°C). Take the dough out of the fridge and roll it out between 2 sheets of parchment paper.

Using a cookie cutter, cut shapes out of the dough and place them on a baking sheet lined with parchment paper. Using a smaller cookie cutter, make a hole in the center of half of the cookies to create a filled center.

Bake for 15 minutes. After baking, let them cool slightly and transfer them to a wire rack.

Step 3: The ganache

Chop the chocolate and place it in a bowl with the butter cut into small pieces.

Heat the heavy cream, but do not let it boil.

Pour the cream over the chocolate, wait 1 minute, and mix with a spatula starting from the center until you get a smooth cream. Set aside.

Step 4: Assembly

Using a spoon, spread the ganache on the smooth side of a non-holed cookie. Add a holed cookie of similar size on top and press gently to let the ganache come out through the hole.

Enjoy!