Apple fritters are popular all over northern Italy, particularly for Carnevale time in February. I've adapted this recipe from an Ada Boni recipe, in Regional Italian Cooking, originally part of the “Gran Fritto” or fry up from Emilia-Romagna. Her recipe calls for only 3 tablespoons of flour, but I found that resulted in fritters that were too soggy and oily. About double the amount of flour makes fritters that are crisp and not oily and that stand up over time. These are even delicious cold, but you can keep them warm in a very low oven. —Emiko
Prepare the batter 30 minutes before you need to use. Beat the egg yolk with the flour and slowly add the milk to create a fluid, smooth mixture rather like pancake batter. Add a pinch of salt and let the mixture rest for 30 minutes. In the meantime prepare the apples by peeling, coring, and slicing into 1/3-inch-thick rounds.
When ready to fry, beat the egg white until stiff and fold it into the batter carefully.
Heat a saucepan that can easily fit 3 to 4 apple rounds with about 1 1/2 inches of vegetable oil (you want the apple slices to float) over medium-high heat. Test the heat of the oil by dropping a blob of batter into it. It should begin to sizzle immediately. Dip the apple rounds into the batter and drop into the hot oil. Cook on both sides until deep golden-brown, about 1 minute total. Cook no more than 3 to 4 rounds at a time.
Drain on paper towels, then dust with confectioners' sugar. Serve warm if possible (but these are also good cold).