For a Christmas dessert with a French touch, this bûche de Noël yule log revisits a great classic of French pastry, tarte au citron meringuée lemon meringue pie, baked as a swiss roll cake. For Christmas or a fancy dinner party.
Mix the egg yolks with the sugar until you get a light yellow color and foamy texture. Add flour and cornstarch (ideally sifted) gradually, stirring regularly.
Whip the egg whites until stiff. Then gently add whipped egg whites to the batter.
Spread the batter evenly on your baking sheet covered with baking paper. You want to have a rectangle about 1 cm thick.
Bake for 10 minutes. Take it out of the oven and immediately roll it up lengthwise in a slightly moist cloth.
Prepare lemon cream
Flavor the sugar. Make very thin zests with 1 lemon and 1 lime (ideally using a Microplane grater) and combine zests with sugar. Let stand 10-15 minutes so that the sugar absorbs the flavors of lemons.
In a saucepan, pour whole eggs and flavored sugar. Combine. Add the lemon juice and heat, stirring constantly. The preparation will gradually thicken (if you have a kitchen thermometer around 82°C / 180°F).
Then set aside in a bowl and let cool down. When the temperature has dropped (around 40°C / 104°F), incorporate the cubbed butter. You can use a handheld mixer mixing to get a smooth texture but be careful not to incorporate too much air. Cover with plastic wrap (touching the preparation so that a crust won't appear) and set aside in the refrigerator.
Prepare syrup
Put all the ingredients in a saucepan and bring to a boil.
Let boil for a few minutes, then set aside to cool down.
Prepare Italian meringue
Bring the water and sugar to a boil and let it boil until the temperature reaches 121°C / 250°F.
When sugar and water start to simmer, start whipping the egg whites. First slowly, then at a higher speed. Sugar syrup should be ready when egg whites become foamy.
While whisking egg whites at high speed, pour hot sugar syrup. Keep whisking until the meringue has cooled down (about 5 minutes, it's over when you can touch the bowl without having a hot feeling.
Dress
Roll out the cake and remove the cloth.
Using a brush, cover cake with a bit of syrup (the idea is to flavor the cake and soften it without soaking it).
Then spread the lemon cream over the entire surface (leave a few centimeters without lemon cream on one length, the part that will be rolled at the end). Then gently roll the biscuit garnished with lemon cream. Place on a plate and place in the refrigerator.
Cover the log with Italian meringue, either using a spatula or a pastry bag, giving the look of your choice. Give a nice golden color using a blowtorch (this is optional). Leave in the refrigerator before serving.