Many years ago when I went to cooking school, the method of learning a core group of formulas was to memorize the ingredients,  known as " bon d'économat." Recently I was asked to make a cake impromptu style. I didn't have my handy formula sheet for Genoise. It's a classic cake in the French repertoire that is made with eggs, sugar, flour as well as a bit of butter and. Working with my dust-covered memory, I managed to summon up amounts for a chocolate genoise which includes cocoa and cornstarch! Can I blow my own bugle? Here goes. It worked! The cake was airy and absolutely what I remembered from school.