LIKE THE EARTH AROUND THE SUN, BUT SLOWER

To make a custard, or a batter, softer, you have to incorporate whipped cream or, depending the cases, whipped egg whites

With a wide and quick motion of a whisk or of electric beater, you add air to your ingredient. In the case of egg whites, the air remains incapsulated within micro-bubbles made of resistent proteins.

In order to keep as much air as possibile in your batter - and therefore to make it fluffier - you have to fold your whipped ingredient with a spatula. Folding requires some coordination: you have to circulate the spatula all around the concave bowl, at the same time rotating it on itself. Just like the earth around the sun, but slower.....