Melt the milk chocolate together with the butter in the microwave or over a double boiler until you get a smooth cream. Don’t overheat the cream; it shouldn’t be boiling hot.

Add the hazelnut spread and chopped hazelnuts, and mix everything together with a spoon to fully incorporate all the ingredients. Place the mixture in the freezer for 15 minutes.

Take out the mixture and form 12 balls, arranging them on a parchment-lined baking sheet.

Place a hazelnut on top of each ball, and gently press down to embed it into the chocolate. Put the chocolates back in the freezer for 30 minutes to firm up.

Melt the dark chocolate in the microwave or over a double boiler until smooth and liquid, then let it cool slightly and thicken a bit.

Now take out the chocolates and, using a fork, dip them into the dark chocolate to fully coat them, allowing excess to drip off for a cleaner finish. Place them back on the parchment paper and let them dry completely. If you’re in a hurry, you can refrigerate them to speed up the process.

Once the chocolate has hardened, lift the chocolates and remove any excess chocolate that may have solidified around the base.