In a large bowl, mash the Banana (1 1/2) with a whisk or fork.
Separate the Egg (6) yolks from the whites and set both aside.
Add half the portion of Milk (100 milliliter) and the 2 of the egg yolks to a large bowl. Mix well.
Stir in the Caster Sugar (70 gram), followed by Cake Flour (15 gram).
In a pot, bring the remaining portion of Milk (100 milliliter) to a simmer.
Pour the heated milk into the mixture in a steady stream while mixing continuously.
Strain the mixture through a sieve. Mash the banana lumps through the sieve with a spoon.
Transfer everything to a pot on low heat. Mix continuously until the custard thickens. The right consistency is when you can draw an "infinite" sign with the custard. Remove from heat and cover with a cling wrap, make sure cling wrap is touching the surface of the custard, or transfer to a piping bag. Chill in the fridge.
To make the meringue, beat 4 of the egg whites and Caster Sugar (40 gram) in a mixer on low speed. When it starts to get frothy, increase to medium. Beat till stiff peaks form.
Preheat the oven at 340 degrees F (170 degrees C).
In a separate bowl, beat the remaining egg yolks, Caster Sugar (40 gram) and Vanilla Essence (1 dash) until mixture becomes creamy.
Add 1/3 of the meringue in Step 1 to the batter in Step 3. Use a balloon whisk to mix, and knock against the side of the bowl to let the mixture fall. Repeat till combined, all the while being careful not to break the air in the meringue.
Sift in the Cake Flour (45 gram) into the bowl and mix till combined.
Add another 1/3 of the meringue and fold in with a spatula. Use the same fold-and-knock motion. When combined, add the final 1/3 of meringue and fold-and-knock till combined. The batter should be smooth and shiny.
Transfer the batter to a baking sheet lined with parchment paper. Gently spread the batter evenly with a spatula. Be careful not to break the air when spreading.
Bake in a preheated oven for 25 minutes. Let it cool before removing from the parchment paper. Trim off the sides but don't throw them away.
Mix Water (2 tablespoon) with Caster Sugar (1 tablespoon) to make the sugar syrup. Spread the sugar syrup on the cake to keep it moist.
Slice the Banana (1).
Spread a layer of banana custard on the sponge cake. Line the cake with sliced bananas.
Make 3 small incisions on each side of the sponge cake and roll gently. Wrap the cake in parchment paper and chill it in the fridge for 1 - 2 hours. You can then slice, serve, and eat!
Cut a slice of the roll cake. Lay it on a dish.
Use the sides of the sponge cake that were sliced off previously and roll the ends to a ball. This makes the ears. Use the sugar syrup to slightly stick it to the cake.
Draw on the face with Chocolate (to taste). Your bear cake is now done!