That Fifteen%

 Clear enough!?

Les dessous de l’impôt mondial de 15 % | La Presse

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So I made an actual sponge cake ie one without added fat,

leavened only by the whisked eggs. Spongy it is, and

will gleefully soak up the juice from fruit salad. Indeed, 

reading up on this cake in Wikipedia, the original was a Spanish

cake that was even more austere: used only egg whites and not the yolks.

Here's the clincher: baking powder was invented in the 20th century, 

allowing for the concoctions of cakes that incorporated those weighy

fats.

Maybe the obesity crisis started there, with desserts!! Seriously, the

infamous Twinkies are a sponge cake with a cream filling.

Below, 1/8th of the recipe, coming in at 200 calories:

https://momsdish.com/recipe/92/perfect-sponge-cake