Preheat the oven to 180°C. Melt the butter on a low heat with the vanilla pod seeds. Leave to cool before blending into the mixture.
Use a mixer to whisk the eggs and the sugar for at least 5 minutes until the preparation is very foamy, then, while continuing to gently whisk, add the sifted flour with the Régilait powdered milk and the yeast.
Next add the melted butter, vanilla extract and fleur de sel salt.
Pour into a cake mould lined with baking paper. Place in the oven, preheated to 180°C, then immediately reduce to 160°C.
Leave to cook for about one hour, until the blade of a knife stuck into the middle comes out dry. Cover with a sheet of baking paper halfway through cooking to prevent the top of the cake becoming too brown.
Leave the cake to cool down before turning it out.