To Make the Cake Layers
Line bottom of an 8-inch round cake pan with baking paper.
In a saucepan, bring milk to a boil, then remove from heat. Add tea bags and steep for 30 mins.
Preheat oven to 175°C with rack in the middle of the oven.
Strain out tea, squeezing out as much liquids from the tea as possible. Discard tea bags. Set aside until cooled to room temperature.
Whisk caster sugar and egg yolks until well combined. Mix in melted butter. Add cooled chai-infused milk, orange zest and vanilla extract. Whisk through thorougly.
Sift over the spices, cake flour, baking powder and salt. Whisk until combined with no lumps.
In a separate mixing bowl, whisk egg whites until frothy using an electric beater or whisk. Add cream of tartar. Whisk until thick foam foams. Gradually add caster sugar. Continue to whisk to achieve firm peaks.
Gently fold in the egg white mixture to the other cake batter in 4 batches. Mix until well combined.
Gently pour approximately 150g of batter into 8-inch cake pan.
Tap the cake pan against the table top to remove any large air bubbles, making sure the batter is level.
Bake for 20 mins until golden brown on top or until tooth pick comes out clean.
Remove cake from the oven, and allow to cool completely.
Using a butter knife, gently slice through the side of the cake pan to loosen it. Unmould cake to a cake board and remove baking paper paper. Peel off the cake skin on top of the cake.
Repeat twice to bake 3 sponge layers.
To Make the Palm Sugar Agar Layers
Mix coconut milk and mung bean flour in a bowl until well combined. Set aside.
Bring water, palm sugar, salt, butter and chai tea bags to a boil in a saucepan over medium low heat, stirring until palm sugar is fully dissolved and palm sugar is melted.
Remove from heat.
Place a sieve over the saucepan, and pour over coconut milk and mung bean flour mixture. Stir till well combined.
Whisk through agar powder until well combined.
Heat the mixture over medium low heat and stir until mixture has thickened but is still able to be poured. remove and discard the chai tea bags.
To Assemble the Cake
Pour a layer of agar mixture to the bottom of a 8-inch springform pan. Wait for 1 min to allow the mixture to cool.
Place a layer of sponge cake on top of the agar mixture.
Repeat 2 times each, finishing with a layer of agar mixture on top.
Allow to cool and place in the fridge overnight to set completely.
Carefully remove the cake from the springform pan and serve. This cake is best eaten chilled.