Pre heat the oven to 180'c
Brush 2 6inch non stick baking tins with the sunflower oil and fit the base with a circle of parchment paper to prevent any sticking.
Fill a large saucepan with water and bring to a gentle simmer.
Break the eggs and place in a large mixing bowl, alongside the caster sugar and the lemon zest.
Place the bowl on top of the pan of water and vigorously whisk for 5 minutes until the mixture resembles a thick custard.
At this stage, gradually sieve the flour into the mixture. When all the flour is sieved, very gently fold the flour through the egg mix using a spatula.
Divide the mixture into the 2 baking tins. Place in the oven for 28 minutes until cooked. Remove the cakes from the tins and allow them to cool on a wire rack.
Wash one tin and dry well, ensuring there is no water. Line the tin with ace-tape. Place one sponge back into the tin, ensuring the flatter side on facing the surface.
Place the milk and the double cream into a deep saucepan. Bring the mixture to the boil. In a large mixing bowl combine the flour, caster sugar and the egg yolks.
When the cream mixture is boiling, pour it over the egg yolks and whisk until it is evenly combined. Return the custard to the pan and keep it on a low heat. Whisk constantly to avoid any lumps. When the custard is thick and silky, remove it from the heat and allow it to cool.
Remove the green part of the strawberries and slice them lengthways. Ensure they are all the same height. Making sure the flat side of the strawberries is at the bottom. Line the outside of the tin with the strawberry slices. If you are finding that the strawberries are not staying in position, try rubbing some sunflower oil round the tin. if you have excess strawberries, place them flat onto the bottom layer of sponge.
When all the strawberries are in place, slowly pour the custard into the centre of the tip, ensuring it covers in the tips of the strawberries. Gently shake the tin to ensure the custard is completely fat. Then place the second sponge on top, ensuring that the flatside of the sponge remains upwards. Gently push the sponge down so the sponge is touching the custard.
Allow the cake to cool and set in the fridge for an hour.
When its set, generously sprinkle the cake with icing sugar and serve.
«Infuse the custard with vanilla or a spirit such an amaretto or brandy for extra flavour.»