How to make
Beat the egg whites and sugar to a fluffy snow. Add the butter (oil), walnuts, flour with baking powder and lemon zest. Stir well, from the bottom towards the top.
Pour it into a buttered and floured tray and bake in a 360°F (180 °C) oven. Once reddened on top, pour on the glaze as well.
To make the glaze, beat the yolks with the powdered sugar and essence, pour it over the baked layer.
Return to the oven, lower it to 130°F (55 °C) and wait for the glaze to dry a bit. It becomes like a meringue.
