4: Pour the vanilla milk-cream mixture into this while stirring or whisking gently.
5: Mix thoroughly.
6: Wash the saucepan, then pour the mixture back into it through a fine strainer.
7: You'll see how this eliminates all the solid bits from the mixture (egg shell, remains of vanilla pod, etc.).
8: Put the pan on low heat and allow the mixture to thicken slightly while stirring constantly. Note: This is not essential, but it makes it easier to bake and set your custard afterwards.
9: Take off the heat, then add 50 g butter and mix thoroughly.
10: Finish by giving a blast with a blender to leave the filling smooth.
11: You flan filling is ready for use in your recipe.