Recently I tried to bake a cake (Caprese) from:
- ground almonds
- dark chocolate
I melted chocolate and butter, mixed all of this with whipped sugar yolks, and then... totally screwed the whipped egg whites, and decided (for science!) to skip folding the egg whites as part of the recipe and just add almonds. As a result, when the cake has actually started to bake, most of the incorporated butter rose to the surface as one slimy puddle.
Why and how egg whites help keep fats inside of cake? I'm mostly interested in chemical or physical explanations of the effect.