Bring 600 ml of water to a boil. Turn off the heat and add 4 tea bags and let them steep for 5 minutes. Squeeze out liquid from tea bags and discard the tea bags
Prepare brown sugar boba pearls:
Bring 600 ml of water to a boil. Add boba pearls and cook for 15 minutes over low heat and then turn off the heat and cover. Let them sit for 30 minutes. We overcook the boba pearls here a bit more than usual so that they won't be hard when you refrigerate your agar agar mooncake in the fridge to set
Put 100 ml water and brown sugar in a saucepan. Let it simmer for 5 minutes. Turn off the heat. Add the cooked boba pearls into the syrup and let them simmer over medium heat for another 5 minutes. Remove and let them cool down
Prepare agar agar mooncake:
Add 400 ml of milk to the milk tea you prepare earlier. Add sugar and agar agar powder. Stir to combine. It helps if you let the mixture sit for about 10 minutes. Turn on the heat and let it comes to a gentle boil and cook until the agar agar dissolves. This is important. If the agar agar isn't dissolved, your cake won't set properly. You shouldn't see anymore specks in the mixture
Assembling:
Fill up the mould about 1/2 way and then add some boba pearls, don't scoop the syrup, just the pearls. Top up with more agar agar mixture until almost full
Let them set at room temperature for about 10 minutes. They won't be fully set yet. Gently transfer to a fridge to let them fully set, it may take about 1 hour or so
Serving: (best served the same day)
Gently push it out of the mould onto a serving platter and serve
The only thing about this bubble tea mooncake is that they are best consumed on the same day. If you refrigerate it for more than 24 hours, the boba pearls tend to harden in the fridge. Cooking the boba pearls longer does help to make them not harden that quickly. So this is not something you want to make in a big batch