Soak the gelatin sheets in cold water one by one until soft (about 5 minutes).

Combine the milk, sugar, heavy cream, tea bags, and vanilla extract in a pot and bring to a boil. Let the tea bags steep for 3-5 minutes.

Remove the tea bags and skim off any tea residue on the surface. Add the softened gelatin (squeeze out the water before adding) and stir until the gelatin dissolves into the milk tea. Strain the milk tea mixture.

Lightly coat the inside of the containers with a little oil, then invert to let excess oil drain out.

Pour the milk tea mixture into the containers and refrigerate for about 3 hours until set.

Cook the ready-made brown sugar tapioca pearls according to the package instructions, then mix with some brown sugar and set aside. Prepare a bowl of hot water, briefly dip the panna cotta containers from the fridge in the hot water, and gently press around the edges to loosen the panna cotta.

Place a small plate on top of the panna cotta, invert it, and gently shake to release onto the plate. Drizzle with the cooked brown sugar tapioca pearls.