Raspberry gratin

Bring water to boil in a double boiler or half fill a saucepan with boiling water to make a bain-marie.
Place egg yolks and sugar in top of double boiler, or in a bowl over boiling water in saucepan, and whisk with electric beater until mixture is thick and creamy.
Gradually beat in sparkling wine. Continue whisking until mixture holds its shape. Immediately place over a bowl containing ice blocks and chill, whisking occasionally, until cool.
Whip cream until stiff peaks form and fold into wine sauce.
Place raspberries in a shallow ovenproof dish and sprinkle sugar and orange liqueur over them.
Bake at 160 ºC for 10 to 12 minutes, or until raspberries have been heated through. Cover berries with wine sauce and place directly under a hot grill for 5 to 6 minutes, or until top turns golden brown.
Remove gratin from grill and serve immediately.