Steps

1. Preheat the oven to 180°C, 160°C fan oven, Gas mark 4.
2. Sieve the flour and baking powder into a large bowl. Add the sugar, vanilla extract, eggs and Stork and mix with a wooden spoon quickly to make a thick batter. Spread the batter evenly into  the prepared tin.
3. Bake the cake in the preheated oven for 25-35 minutes until golden brown. Leave the cake to cool on the baking sheet.
4. While the cake is in the oven, make the custard cream: Heat the milk to a simmer. Mix the custard powder in a bowl with the sugar, egg and 4 tablespoons of warm milk. Pour the mixture into the hot milk, stirring constantly, bring the custard to a simmer  and cook for 3-4 minutes on a low heat. Stir regularly. Allow the custard to cool while stirring occasionally to prevent a skin forming on the top.
5. Meanwhile clean the strawberries and halve them.
6. Whip the cream until stiff. Fold the whipped cream into the cold custard (if the custard is warm or hot, the cream will melt, making the cream too thin!). 
7. Spread the custard cream evenly over the cake.
8. Spoon the strawberries on it, dust the cake with icing sugar and cut into 8-10 slices.