Halloween purple sweet potatoes custard cake

Halloween is around the corner and today I am baking a chocolate Cake filled with purple sweet potatoes cream and custard cream.

Recipes:

chocolate sponge cake

eggs : 2 pieces (60g each)

sugar : 30g (egg yolk)

sugar : 30g (egg white)

Cake flour : 50g

cocoa powder: 10 g

unsalted butter: 20g

milk : 16g

custard cream

Egg yolk: 2 pieces

corn starch: 8g

cake flour: 8g

milk: 200g

Sugar: 30g (15g for egg yolk; 15g for milk)

Vanilla essence: 1/2 teaspoon

purple sweet potatoes cream

purple sweet potatoes paste: 150g

Whipping cream: 60g

sugar: 20g

decoration cream

whipping cream: 300g

sugar : 30g

white chocolate: as needed

dark chocolate: as needed

sugar syrup

sugar: 32g

water:80g