Chocolate Ganache

1. Combine the chocolate, cream, and butter in a heatproof bowl and heat in the microwave or over a double boiler until melted
2. Stir until completely combined, cover with cling wrap, and place in the fridge to chill for 1-2 hours or until completely firm
3. Line a baking tray with parchment paper
4. Divide the ganache into 8 portions and roll them into balls
5. Place the balls on the lined baking tray and refrigerate for 30 minutes or until firm

Mochi

1. Combine the glutinous rice flour, sugar, cocoa powder, and cornstarch in a medium-sized microwave-safe bowl, and whisk to combine
2. Pour in the milk into the dry ingredients, and whisk until smooth
3. Cover the mochi mixture with cling wrap and microwave for 2 minutes on high
4. Uncover and stir
5. Then re-cover and microwave for another 2 minutes, the mochi dough should be semi-translucent
6. If the mochi is still slightly liquidy/milky re-cover it and microwave at 1-minute intervals until cooked through
7. Allow the mochi to cool enough to handle
8. Add the vegetable oil and using gloved or oiled hands knead until smooth
9. Prepare a baking tray lined with baking paper
10. Divide the mochi into 8 equal portions and place on the baking sheet.

Assembly

1. Put the cocoa powder in a shallow bowl
2. Flatten a ball of mochi in your palms
3. Add a ball of chocolate ganache in the center and pull the sides of the mochi over it to enclose the ganache, pinch to close
4. Roll the assembled mochi in the cocoa powder
5. Repeat until all the mochi and ganache have been used