In a medium sauce pan, heat the milk, butter and vanilla together, by stiring occasionally. The mixture is ready once the butter has melted and that it is hot and not boiling.
Then, stir in the Nutella, and continue to stir until it has fully melted. Set aside.
In a mixing bowl, gently whisk together eggs + yolks, sugar and flour.
Pour a little at a time the milk mixture over the eggs mixture by stirring continuously.
Cover the mixing bowl with cling film and refregirate for an hour.
Preheat oven at 410F/210C.
Using the mini ladle, pour your batter into the Flexipat® leaving about 0.5"/1cm to the top.
Bake for 40 minutes at 410F/210C. (Every oven heats differently, monitor your Canelés from 30min)
Once your Canelés are out of the oven, let them cool down for about 10min. Then, Unmold and let them cool completely before serving them. Enjoy!