BIRD'S MILK CAKE 🐦🍶

WE WILL NEED
FOR THE SPONGE CAKE:
4 egg yolks
50 grams powdered sugar
50 grams butter at room temperature
80 grams wheat flour (sifted)
0.5 teaspoon baking powder (3 grams)
A pinch of vanilla (or 5 grams vanilla sugar)
FOR THE SOUFFLÉ:
100 g butter at room temperature
150 g condensed milk
4 egg whites
150 g sugar + 75 g water (for the syrup)
1 tbsp lemon juice (10 g)
Gelatin 15 g + 50 g water (for gelatin)
FOR THE MIRROR GLAZE:
Cocoa powder 40 g (3 tbsp)
Sugar 120 g
Milk 200 g
Gelatin 7 g