Gather all your ingredients: 1 cup of melted chocolate, 1 cup of heavy cream, ½ cup of softened unsalted butter, and ½ cup of chopped toasted hazelnuts.

In a mixing bowl, combine the melted chocolate, heavy cream, and softened unsalted butter. Whisk for about 2-3 minutes until glossy and smooth.

Gently stir in the chopped toasted hazelnuts until evenly distributed.

Allow the filling to cool at room temperature for 10-15 minutes until thick but spreadable.

Check the consistency; if too soft, refrigerate for 5-10 minutes.

Use the filling as desired or transfer to an airtight container and refrigerate for up to a week.