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 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 parchment paper
10. Divide the mochi into 8 equal portions and place on the baking sheet.

Nutella Cream

1. Combine the cream and Nutella in a large bowl and beat with an electric mixer until it reaches stiff peaks
2. Transfer the cream to a piping bag fitted with a large round nozzle and place in the fridge until assembly

Assembly

1. Put the cocoa powder in a shallow bowl
2. Dust a ball of mochi in cocoa powder and use a rolling pin to flatten it into a circle
3. Pipe a blob of Nutella cream in the center, and pipe a smaller dollop of Nutella on top
4. Pinch the sides of the mochi together into the center to seal
5. Roll the assembled mochi in the cocoa powder
6. Repeat until all the leftover dough and filling have been used