Roast the whole hazelnuts in a frying pan on medium heat. Once golden, place them on a clean cloth, fold the fabric and roll them on a table to remove their skin, which makes the hazelnut bitter.
Coarsely chop the hazelnuts and place them in a food processor. Process them initially on high, reducing the hazelnuts to a powder. Continue to mix. The hazelnuts will produce an oil and form a paste. However, make sure to pulse the food processor so that it does not overheat.
Then, place the mixture in a bowl.
Chop the chocolate with a knife and pour into the bowl with the hazelnut paste.
In a saucepan, bring the heavy cream and sugar to a boil and pour this immediately into the bowl, cover and wait 5 minutes for the chocolate to melt.
Once melted, mix until the mixture forms a smooth paste and then incorporate the hazelnut oil. Mix well and divide into airtight jars.
Spread can be kept at room temperature for more than a month.