Magic Custard Cake Recipe

"Adapted from Mabel's "Tart Magica". Temperatures for the ingredients are important here. Not too warm to cook the eggs before baking, and not cold either. You can use either confectioner's sugar or regular sugar, use the same amount by weight but the volume will be different. If you use regular sugar, 150g will equal 3/4 cup. We noticed on the the site were we originally found the recipe that her top was fluffier. After reading through the google translations we noticed she added 4 drops of vinegar to the egg whites when whipping. That would have made them more stable and probably resulted in a fluffier top. Whipping the egg whites in a copper bowl would accomplish the same thing. Next time we make it, that will be the plan...."