First, melt the good quality chocolate with a high cocoa content and butter in a double boiler and let it cool slightly.

In a bowl, add the sugar, eggs, vanilla, and a pinch of salt. Beat well with an electric mixer until the mixture is light and fluffy.

Add the melted chocolate mixture once it has cooled, and stir with a spatula until well combined.

Then add the flour and baking powder, and stir with a spatula until you have a smooth mixture.

Cover the mixture with plastic wrap and place it in the refrigerator for 30 minutes to cool and firm up the dough.

Take a portion of the dough, flatten it in your hands, fill it with Nutella, and shape it into a flat ball. Place it on a baking sheet lined with parchment paper.