Start by scooping out 9 balls of ice cream. I made mine about 1 inch in diameter.
Place the balls of ice cream on a baking sheet, or in muffin liners, and place them in the freezer while you are preparing the mochi dough.
In a bowl, combine the sweet rice flour, sugar, cacao, and milk. Mix them well.
Cover the bowl with plastic wrap and poke some holes into it. Microwave the dough for 1 minute in the microwave.
Remove the plastic wrap, mix the dough with a spatula, then cover again and microwave for another minute. Repeat this three times in total.
The mixture should have formed a sticky dough. I like to place the dough in the freezer for 30 minutes so make it slightly less sticky.
After the dough has chilled, generously flour a surface with cornstarch (I really mean generously! The dough is very sticky).
Place the dough on the surface, and sprinkle another generous amount of cornstarch on top of the dough.
Using your hands or a rolling pin, flatten out the dough. Then use a knife to divide it into 9 squares that are about equal in size.
Take each dough ball and flatten it out until you have a flat disk (should look something like a mini pizza dough). Make sure you are using plenty of cornstarch so that the dough doesn't fall apart.
Take out the frozen ice cream scoops. Place an ice cream scoop in the middle of the dough ball and gently enclose the ice cream inside the dough until the ice cream is fully enclosed.
Repeat this for each mochi ball and immediately put them in the freezer once you make each one.
Freeze them for at least 30 minutes (or store them in the freezer for as long as you want to always have a yummy snack on hand!)
Enjoy your mochi!