Sift flour and set aside. In a stand mixer fitted with the whisk attachment, beat eggs with egg yolks and sugar until foamy. Fold in sifted flour. Spread mixture evenly onto a greased parchment paper and bake.
Bake biscuit roulade at 425ºF/220ºC for 6 to 7 minutes. Cool to room temp, top with a kitchen towel and roll ou; set aside.
Bring to boil lemon juice, sugar and eggs whisking constantly. Cool to 140ºF/60ºC and add the chilled and cubed butter; blend well – store in refrigerator for up to a week.
In a stand mixer fitted with the whisk attachment, start to beat on medium-speed room temperature egg whites with cream of tartar or a few drops of lemon juice. Keep meringue to foamy stage prior pouring in the cooked sugar in thin stream. Cook sugar and water to 250ºF/121ºC. Beat until it cools down and use. Extra Italian meringue can be stored in the freezer for weeks for later use such as mousses, fillings, buttercream and so on...
Spread evenly lemon crémeux over the biscuit. Roll out into a log, and freeze to set. Coat with Italian meringue. Torch before serving or throw in a 450ºF/230ºC oven for about 5 min. Enjoy!