Preheat the oven to 200°C.
Melt the chocolate in a bain-marie with the butter.
In a bowl, break the eggs, add the sugar.
Blanch the preparation with the beater to obtain a compact foam.
Add the chocolate, then the flour, mixing gently.
Butter the ramekins or fondant molds.
Cut truffle into 6 equal parts.
Pour the fondant mixture into three quarters of the moulds.
Insert a piece of fresh truffle and cook at 200°C for 6 minutes.
Serve hot or cold.