Preheat the oven to 338 degrees F (170 degrees C).
In a clean bowl, whisk in yolks of the Egg (3), Caster Sugar (1 tablespoon), Blackcurrant Powder (1 tablespoon), Blackcurrant Jam (35 gram) and Blackcurrant Concentrate (3 teaspoon) until well combined. Next, drizzle in Water (3 tablespoon) and Vegetable Oil (5 tablespoon).
Stir in All-Purpose Flour (60 gram), Corn Starch (15 gram) and Baking Powder (1/2 teaspoon).
In another clean bowl, whip egg whites and Distilled White Vinegar (to taste) until frothy. Sprinkle in Caster Sugar (2 tablespoon) while whipping on high speed until stiff peaks.
Fold the blackcurrant mixture into the whipped egg whites.
Pour into a 6-inch removable round cake pan, tap it a few times against the counter to get rid of air bubbles, then bake in the oven for 45 to 55 minutes.
Let it cool upside down.
Microwave Gelatin Powder (1/2 teaspoon) and Water (2 teaspoon) together for 5 seconds until it heats up. Let it cool.
Whip Whipping Cream (100 milliliter), Caster Sugar (1/16 cup), Blackcurrant Powder (3 teaspoon) and Blackcurrant Concentrate (1 tablespoon) until soft peaks. Then stir in gelatin mixture and Natural Unflavored Yogurt (50 milliliter). Continue whisking until stiff peaks form.
Pipe the cream onto the cooled cake. Decorate with fresh berries, mint leaves, and white chocolate buttons if desired.