1. Grease and line a 30 x 20 cm (12 x 8 inch) jelly roll tin.
2. Place the eggs and sugar in a bowl and whisk with an electric whisk for about 10 minutes, until the mixture is very thick and mousse-like.
3. Carefully fold in the flour and ground walnuts.
4. Turn into the prepared tin and bake in a preheated oven, 190°C/375°F, for 20-25 minutes. Turn onto a wire rack to cool.
5. Set aside a quarter of the cream and a few strawberry slices. Fold the other strawberries and cream together.
6. Cut the cake into 3 equal pieces widthways and sandwich together with the strawberry and cream filling.
7. Spread some of the remaining cream over the sides of the gateau and coat with the chopped walnuts.