These sundaes require about 1 1/4 cup-capacity stemmed glasses, coffee cups or mugs. Let the sundaes stand for about 30 to 40 minutes at room temperature before serving as the sauce should be soft, the sherbet still rather firm.
Strawberry Romanoff Sundaes
Quarter the strawberries, spread them in a single layer on a baking sheet and freeze them until they are almost solid, 20 to 30 minutes.
Place the berries in a food processor with the sugar and orange zest. Pulse to chop the fruit, then process continuously until the berries are pureed. Add the rum and preserves. Process briefly to mix. With the processor running, add the cream through the feed tube in a steady stream. Process until just mixed. Transfer the mixture to a plastic container and freeze until it’s firm enough to scoop, about 2 hours.
Whip the cream and sugar until thick. Transfer it to a bowl. Whip the ice cream until it’s thick and pourable. Fold it into the whipped cream along with the rum and Cointreau.
Use a 1/4-cup scoop for sherbet, putting 1 scoop in each of 6 stemmed glasses. Top each with 1/4 cup of sauce. Add another scoop of sherbet and then more sauce to cover. Place the sundaes in the freezer several hours or overnight, covered airtight.
To serve, let the sundaes rest at room temperature to soften slightly, 30 to 40 minutes. Top them with sliced strawberries, if using. Serve immediately.