1. Peel the yam and steam it, then use a rolling pin to press the yam into a puree, and then put it into a slightly larger bowl with yogurt, milk powder, and starch.
2. Mix it evenly with a rubber spatula, and then filter some with a sieve, so that the taste will be more delicate.
3. Pour the egg whites into the egg beater, add 5g of white sugar, and then beat them with a whisk.
4. In the process of whipping, pour all the remaining white sugar into the egg-beating bowl, and beat the egg whites to a dry foaming state (that is, nine parts).
5. After the egg whites are beaten, use a rubber spatula to scoop out 1/3 of the egg whites and put them into the reconciled yam puree, and then mix them evenly.
6. After the yam and egg whites are mixed, pour them back into the egg-beating bowl, and then mix them evenly with a rubber spatula. Be sure to turn them up and down when turning, otherwise the egg whites will defoam very easily.
7. After the protein is mixed, put it in a piping bag.
8. Prepare a baking tray, cover it with greased paper, and evenly squeeze the egg whites on the greased paper, leaving a little distance between the two to prevent sticking together during baking.
9. Preheat the oven, heat the upper and lower middle layers, and bake at 150°C for 15 minutes. If burnt occurs during the baking process, a layer of tin foil can be added halfway. Since the actual temperature of each oven is not the same here, there will be some discrepancies in the temperature during baking, which can be adjusted according to the actual situation. If you don't have an oven, you can also use a pan to sear directly, and the taste is the same.
10. The finished product!
