Instructions

1. Start by making mochi doughnuts. In a microwave-safe bowl, use a fork to stir ¼ cup (60 ml) sweet rice flour and ¼ cup (60 ml) milk. Microwave on high for 15-second intervals, stirring between cooking times, until a sticky dough forms, 30 to 45 seconds in total. Set aside and let cool to room temperature.
2. Meanwhile, in a medium mixing bowl, whisk remaining 1¾ cups (430 ml) rice flour, remaining ½ cup (125 ml) milk, tapioca starch, sugar, salt and baking powder. Set aside. In a small bowl, whisk egg and melted butter. Set aside.
3. To dry ingredient bowl, add cooled mochi dough and egg mixture. Stir with a wooden spoon until dough comes together. Continue to knead dough in bowl until smooth and only slightly sticky. Dough should be able to hold its shape. Add a little more rice flour as needed.
4. Pour vegetable oil into a large heavy-bottomed saucepan to come 2-in (5 cm) up sides. Fit saucepan with a deep-frying thermometer and heat oil over medium until thermometer registers 350 F (175 C).
5. Cut a large piece of parchment into eight 4-in (10 cm) squares and set aside.
6. To shape doughnuts, lightly oil your hands and divide dough into 8 equal portions. Working with 1 portion of dough at a time, divide portion into 8 pieces and roll into balls. Arrange 8 balls in a circle on a parchment square, making sure balls are touching. Transfer parchment with doughnut ring to a rimmed baking sheet. Repeat rolling and shaping process to make 7 more doughnut rings.
7. Working with 1 doughnut ring at a time, carefully pick up a parchment square and lower it, paper-side down, into oil. Fry for about 45 seconds, then carefully remove parchment with tongs and discard. Continue to fry doughnut until golden brown, about 2 minutes per side. Take care not to flip too early or doughnut may break apart. Carefully transfer to a rack and let cool. Repeat cooking process with remaining doughnuts.
8. While doughnuts cool, make glaze. In a medium bowl wide enough to dip doughnuts into, whisk icing sugar, milk and desired amount of ube extract. Adjust consistency as desired with milk, 1 tsp (5 ml) at a time.
9. Dip tops of doughnuts in glaze, letting excess drip back into bowl, and return to rack. Let sit until glaze is set, about 15 minutes.
10. Melt white chocolate chips in a double boiler. Drizzle over doughnuts and let white chocolate set for 15 minutes. Doughnuts are best eaten the same day they are made.