Peel the oranges with a sharp knife so that the white skin is completely removed. Cut the oranges into thin slices crosswise and arrange them nicely on a deep glass plate. Sprinkle with 40g sugar and drizzle with 5 tablespoon arrack or rum. Chill for at least 2 hours.
Beat egg yolks and remaining sugar until frothy. Whip the cream until stiff and fold into the egg yolk mixture, also chill for 2 hours. Just before serving, stir the remaining rum or arrack into the cream.
Either serve the cream and orange slices separately or pour the cream over the oranges and serve. If children eat with them, just leave out the alcohol, it tastes so good too.