Danish Chocolate and Custard Gateau Recipe

4 eggs, separated
175 g/6 oz/1 cup icing (confectioners') sugar, sifted
Grated rind of 1/2 lemon
60g/2.5 oz plain (all-purpose) flour
60g/2.5 oz potato flour

2.5 ml/0.5 tsp baking powder
For the filling:
45 ml/3 tbsp caster (superfine) sugar

15 ml/1 tbsp cornflour (cornstarch)

300 ml milk
3 egg yolks, beaten
50 g/2 oz chopped mixed nuts

150 ml double (heavy) cream
For the topping.
100g/4 oz/1 cup plain (semi-sweet) chocolate
30 ml/2 tbsp double (heavy) cream

25 g/1 oz white chocolate, grated or sliced into curls

Method:

Beat the egg yolks into the icing sugar and lemon rind. Stir in the flours and baking powder. Whisk the egg whites until stiff, then fold into the mixture using a metal spoon. Spoon into a greased and lined 23 cm/9 in cake tin (pan) and bake in a preheated oven at 190°C/375°F/gas mark 5 for 20 minutes until golden brown and springy to the touch. Leave to cool in the tin for 5 minutes, then turn out on to a wire rack to finish cooling. Slice the cake horizontally into three layers.

To make the filling, blend the sugar and cornflour to a paste with a little of the milk. Bring the remaining milk just to the boil, then pour on to the cornflour mixture and blend well. Return to the rinsed-out pan and stir continuously over a very gentle heat until the custard thickens. Beat in the egg yolks over a very low heat without allowing the custard to boil. Leave to cool slightly, then stir in the nuts. Whip the cream until stiff, then fold into the custard. Sandwich the layers together with the custard.

To make the topping, melt the chocolate with the cream in a heatproof bowl set over a pan of gently simmering water. Spread over the top of the cake and decorate with grated white chocolate.