1. To make the cake, heat the oven to 170C/325F/ gas mark 3. Butter and flour two 23cm sandwich tins.

2. Sift the flour, baking powder and three quarters of the caster sugar into a large bowl. Using an electric mixer beat in the water, egg yolks, melted butter and vanilla extract until the batter is smooth.

3. With clean beaters, whisk the egg whites until softly peaking, add the remaining caster sugar and whisk again. Fold quarter of the egg whites into the batter to loosen it, then carefully fold in the rest, pour into cake tins and level.

4. Bake for 20-25 minutes until a skewer comes out clean when inserted.

5. Remove the cake from the oven and cool for a few minutes before turning onto wire racks to cool completely.

6. To make the frosting, break the chocolate into a bowl, add the butter, and set the bowl over a pan of simmering water until melted. Remove from the heat and add the dulce de leche. Add the icing sugar and beat until smooth.

7. Place one cake on a flat plate, spread the raspberry conserve over evenly, then spread over the cream. Cover with the second cake. The frosting should still be of a soft spreading consistency, spoon over the top of the cake and allow to fall over the sides, spreading it around the sides and over the top evenly. Mound the berries on top and refrigerate for 2 hours to set the frosting.