Beat the cream with the icing sugar and vanilla until stiff peaks are formed.
Store in the refrigerator until use.
Preheat the oven to 180 degrees Celsius.
Make a meringe by mixing the egg whites with the tartaric acid and a pinch of salt until it is frothy.
Little by little add half (75 grams) of sugar and mix until it is stiff.
In a second bowl, mix the egg yolk with the rest of the sugar until it becomes light yellow.
In the second bowl, add the vanilla extract, lemon juice, melted butter and whipped cream and mix until completely mixed.
Golden curls (optional)
Draw beautiful curls (or other patterns) on a 25 x 37.5 cm baking paper and turn the baking paper over and place it on a baking tray of the same size (optional)
In a small bowl, mix 3 tablespoons of the egg yolk mixture with 6 tablespoons of the meringue mixture and a few drops of golden dye and fold with a spatula until everything is mixed.
Fill a piping bag with point 2 with this mixture.
Pipe the decorative curls as you have drawn them on the baking paper with a small nozzle.
Bake for 5 minutes until the curls are firm.
Add purple and red dye to the egg white batter. (optional)
Carefully fold the egg white mixture through the egg yolk. Start with ⅓ of the mixture so that it can get used to each other and then add the rest of the egg whites.
When the baking tray comes out of the oven after 5 minutes (if you use a second pattern), carefully pour the rest of the batter onto the baking paper. Carefully smooth out the batter. If you make a smooth cake without patterns then you can omit this step.
Bake the cake for 10 minutes or until a skewer comes out dry. (or 15 minutes when you make an even cake).
Remove the cake from the oven and roll it up. This way it gets used to the round shape and does not break when you fill it.
Allow the cake to cool, roll it gently open and fill with the cream. Then roll the cake again and let it set in the fridge for at least 2 hours
Optional: Decorate with stars / crowns and golden whipped cream tufts.