Sieve through the sweet rice flour and self raising flour into a large bowl. Add the melted butter and salt. Gradually pour in hot milk. As you pour down mix all the ingredients well. Knead it to make one large dough.
Take the dough out onto a cutting board and divide it into smaller pieces to make mini round balls. (The size can be up to you but remember that larger donuts take longer to cook. Also make sure it is large enough to hold the stuffing inside.) While working through, cover the mini balls with glad wrap to stop them drying out.
Place a rolled donut ball on your palm and flatten it by pressing it with your thumbs. Add a spoonful of nutella and seal the dough. (I added 1/2 tsp worth stuffing in each ball. You could add more or less, just make sure you can close the dough without getting messy.) Set aside. Repeat this with the remaining ingredients.
Pour some oil for frying in a deep sauce pan and heat it for 6 to 8 mins (until boiling) on medium heat. Add the donut holes gently (about 5 at a time, depending on the size of your pan) and fry them until the outer dough is golden brown and the inside dough is cooked through. (It takes 5 to 6 mins for mini holes and 7 to 8 mins for medium holes.) While frying, continuously roll the donut balls around so they don't stick to the base of the pan, and to shape them better. Place the cooked donuts onto a piece of oil absorbing paper and cool down for 10 to 15 mins. Repeat this with the remaining ingredients. Be sure to watch out for oil splash. You may want to wear a long apron.
In a medium or large sized food grade plastic bag, add the sugar and cinnamon powder. While holding the top of the bag with one hand, shake it so that the sugar and cinnamon gets mixed together. Add the donut holes (5 or 6 at a time, depending on the size of your bag) into the bag and shake it so that the donuts get coated with cinnamon flavoured sugar. Repeat this with the remaining donut holes. Serve. (It tastes best within the first hour of making them.)