1: Pour 750 ml milkinto a saucepan on low heat. Scrape 1 vanilla pod into the milk, add 1 vanilla pod zest and bring to the boil. Take off the heat, cover and leave to infuse for 10 minutes.
2: Preheat the oven to 390°F (200°C). Pour 3 eggs and 1 egg yolk into a blender goblet, then add 60 g caster sugar, 60 g flour and 1 pinch salt.
3: Blend on high speed until the mixture turns pale.
4: Reduce the speed slightly, then pour in the vanilla-flavoured milk. Blend for a few seconds longer to mix.
7: Top with slivers of butter and bake for 30 minutes.
8: Serve straight from the tin, as the flognarde will be very fragile.
Remarks
For a version with fruit, such as apples, sauté the peeled fruit in a little butter and sugar, then lay in the bottom of the tin or mould before adding the filling mixture. For a nicely browned top, sprinkle the top of the flognarde with caster sugar after the first 10 minutes of cooking.