Preheat the oven to 180 degrees C. Bake the slices of bread on a baking tray for about 20–30 minutes, or until they have turned golden brown and dried into rusks.
Remove the rusks from the oven and set aside until cool, then grind into ﬁne crumbs in a food processor or put into a strong plastic bag and crush ﬁnely with a rolling pin.
Put a third of the crumbs in a saucepan, add the sugar, milk and cream and bring very slowly to the boil, stirring continuously. As soon as boiling point is reached, remove the pan from the heat and pour the mixture through a nylon sieve into a bowl. Set aside and allow to become completely cold, then stir in the remaining crumbs and the amaretto or the maraschino liqueur.
Freeze as for vanilla ice cream either in the freezer or in an electric ice-cream maker.