Preheat the oven to 300°F. Then, grease and line a 15-cm round cake pan with parchment paper.
2. Step
Melt butter and milk in a pot. Then, transfer to a medium bowl and add in all the flour at once. Whisk and cool.
3. Step
Add in egg yolks one at a time. To this, add vanilla extract.
4. Step
Beat egg whites and sugar until a stiff peak forms. Once done, gently fold in ⅔ of the egg whites into the egg yolk mixture. Pour this into the egg white mixture and fold together.
5. Step
Pour everything into your cake pan and bake in a water bath for 30 minutes.
