In a saucepan, steep 5g of black tea leaves in 180g of milk over low heat to create a milk-tea mixture. Allow the tea leaves to infuse into the milk for a rich flavor.

In a mixing bowl, combine 30g of corn starch, 30g of sugar, and 100g of glutinous rice flour. Slowly pour in the prepared milk tea while stirring continuously to create a smooth batter.

Sift the batter once to remove any lumps and ensure a smooth consistency.

Cover the bowl with plastic wrap, poke holes in the wrap to allow steam to escape, and steam the mixture for 25 minutes in a pan until it becomes firm and cooked.

After cooking the mochi dough, take it off the heat and incorporate 15g of butter while it's still hot. Stir until the butter melts completely. Once the dough has cooled down, Stretch it for approximately 5 minutes until it reaches a smooth and elastic consistency.

In a separate bowl, whisk together 300g of whipped cream and 20g of sugar until smooth and creamy. Transfer the whipped cream mixture into a piping bag for easy filling.

Divide the mochi dough into 8 equal portions and roll each portion into a thin sheet.

Place the mochi sheets into molds (I use small bowls). Pipe the prepared whipped cream filling onto the center of each mochi sheet and add boba pearls as desired.

Carefully wrap the mochi around the filling to encase it completely. Trim off any excess dough with scissors, then flip the mochi over and gently press down on it with the pointed end of a rolling pin to create a slight indentation. You can optionally add boba pearls at this stage.

Once assembled, your homemade Boba Milk Tea Mochi is ready to be enjoyed! Serve the mochi immediately or refrigerate for a firmer texture.