Scald the flour in a bowl with the hot milk, and stir immediately until smooth with a whisk or wooden spoon.
Let cool to lukewarm, then add the rum, salt and egg yolks. Beat vigorously until smooth and glossy.
Whisk the egg whites to stiff peaks, and gently fold into the dough in two or three batches, to keep it light and airy.
Heat plenty of oil or lard to 170°C.
Drop small dumplings of the mixture into the hot fat with two teaspoons, and fry over medium heat for 3-4 minutes, turning occasionally, until golden brown.
On a plate, mix the vanilla sugar with the grated chocolate.
Roll the freshly fried fritters immediately, while still warm, in the chocolate-vanilla sugar.
Serve warm.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.