Melt the butter and leave to cool slightly.
Combine all the dry ingredients in a bowl. Whisk in the milk, egg yolks, melted butter and lemon zest.
Beat the egg whites until stiff and fold carefully into the batter.
Heat a donut pan and grease with a little melted butter.
Drop in the mixture until it almost fills the hollow in the pan. Turn them round half a circle and continue cooking until cooked through. Tip: Use a skewer or fork.
Place the prepared apple slices on a plate with icing sugar.
When they are all done, sprinkle generously with icing sugar, dip them in a tasty jam and enjoy!
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