Line a pound cake tin with parchment paper. Break the eggs into a bowl and beat them well with a whisk. Add the milk, skimmed milk powder, and sugar in that order, mixing after each addition.
Sift the flour and baking powder into the mixture and mix until no longer lumpy. Then pour the batter into the pound cake tin.
Loosely cover the tin in cling film and heat in the microwave for 4-6 minutes (600 W) (refer to the Helpful Hints section here). When the cake is cooked through, it's done!
Story Behind this Recipe
I was selected to try out a brand of baking paper and so decided to use it to make a snack. The baking paper I used helped me slide the sponge easily off.
Please adjust the cooking time based on your type of microwave and the wattage. (If the cake looks like it is cooking through a bit fast, you can reduce the time). If you increase the cooking time by just a bit, the bottom of the cake will go a bit crispy. I kind of like that so I make the top 2/3 fluffy and the bottom 1/3 crispy. This is a castella-style sponge, not a castella sponge itself.