To prepare the filling, process the

hazelnuts in a food processor for a few minutes, until you have a paste-like nut butter. Add oil and continue processing for another minute. Pour melted chocolate into the food processor. Process for another few seconds until the mixture is smooth.

Pour the mixture into a silicone baking mold with one-and-a-half-inch (three-to-four-centimeter) depressions or into an ice cube tray and freeze for three hours, then release from molds.

To prepare the dough, mix all ingredients into a soft dough and refrigerate for one to two hours.

Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).

Remove the dough from the

refrigerator. For medium cookies, divide the dough into 20 pieces; for large ones, divide it into 10. Flatten each piece of dough into a circle. Put a frozen hazelnut butter circle on top and roll it into a ball.

For perfectly round cookies, place the cookie balls inside metal cookie cutters or in a muffin pan and bake for about five minutes.

Remove from the oven and sprinkle with the halved hazelnuts and salt. Return to the oven for another eight to 12 minutes (depending on the size of the cookies), until they begin to brown and get crispy on the edges but are still a bit soft inside.

Cool and store at room temperature

for up to four days. These cookies can be stored in the freezer for up to two months.