Preheat oven to 180°C. Place the pudding mix in a large bowl. Add the egg and water. Use an electric beater to beat on low speed until just combined. Increase speed to medium and beat for a further minute or until the mixture thickens slightly.
Use a spoon to fold in raspberries until just combined. Spoon egg mixture into a 1.5L (6-cup) capacity ovenproof dish. Sprinkle sauce mix from the pudding mix packet evenly over the egg mixture.
Carefully pour the boiling water over the egg mixture. Bake in oven for 35-40 minutes or until a cake-like top forms and the centre springs back when lightly tapped. Dust with icing sugar and serve immediately with ice-cream.