How to make
Lay out a medium-sized tray with baking paper and melt the butter in it.
Separate the egg whites from the yolks and beat the whites in a clean, dry bowl with 1/3 cup sugar. If the eggs were at room temperature, you should have no problem obtaining a nice snowy mixture.
In another bowl, beat the yolks and remaining sugar until the mixture doubles. To them, add the slightly cooled butter and stir well. To this mixture, add the flour which you've sifted beforehand and stir again.
Pour in the slightly heated milk (heated in order to homogenize the mixture easier) and add the liqueur.
Add the egg whites to the egg yolk mixture, while stirring carefully in one direction until you get a homogeneous mixture. Don't worry if the mixture seems runnier than the usual cake batter.
Pour it into the form and bake at 340°F (170 °C). Depending on the oven, you can leave just the bottom element and fan on once it's heated well.
It's ready once the upper layer firms up and the crust browns. If using a toothpick to check on it, only its upper half will be dry because the lower layer will remain slightly creamy. And that's why it's a magic cake!
It's best to leave it in the oven a little before taking it out to cool fully.
When serving, sprinkle with powdered sugar.
You can eat it while it's still warm too. You'll still be able to taste both of the delicate layers - the light layer on top and the soft pudding-type cream on the bottom.
