Peel the taro and cut it into small pieces. Steam for 15-20 minutes until a chopstick easily pierces through the pieces.

Place the steamed taro in a blender, add purple sweet potato powder, sugar, milk, and butter.

Blend until the mixture is smooth and creamy. If needed, blend longer for a finer texture. Transfer to a piping bag and set aside.

In a mixing bowl, combine glutinous rice flour, purple sweet potato powder, cornstarch, and sugar. Mix well.

Gradually pour in milk while stirring until a smooth batter forms.

Sift the batter for a finer texture. Cover with plastic wrap and poke a few small holes with a toothpick.

Steam the batter over high heat for about 20 minutes. Once cooked, remove and add 15g butter while the dough is still warm. Stir to melt the butter, then knead the dough with gloved hands until smooth and elastic.

Soften cream cheese at room temperature and mix with granulated sugar.

Gradually pour in whipping cream, whisking on low speed until combined. Increase speed to medium and whisk until fluffy with soft peaks. Transfer to a piping bag.

Divide the prepared glutinous rice dough into 20-30g portions (adjust size to your preference). Roll each portion into a thin round sheet.

Place a sheet into a small bowl-shaped mold. Pipe a layer of cream cheese filling, then a layer of taro paste onto the center.

Gather the edges of the dough and pinch them to seal the fillings inside. Trim any excess dough.

Lightly coat the finished mochi with purple sweet potato powder to prevent sticking. Repeat with the remaining dough and fillings.