Pre-heat oven to 160ºC. Grease 20cm cake tin with butter, add in some self-raising flour and shake around until the whole tin is covered with flour.
Separate the egg whites and yolks, whip the egg whites on low speed and once the egg whites start to turn white add tablespoon of sugar and whip until soft peaks. Mix egg yolks, two tablespoon of sugar and whip until fluffy and pale in colour, add tablespoon of flour followed by table spoon of whipped egg whites and gently mix. Follow by adding another tablespoon of flour and tablespoon of whipped egg whites. Once incorporated, add everything into the rest of the egg whites. Fold the mixture in gently so you won’t loose the air form the egg whites. Transfer the batter into the cake tin and bake for about 10-12 minutes, until the sponge is golden brown and starts separating form the sides of the tin. Let it cool completely. The sponge will be low and look dense, do not worry, that's normal.
To prepare your strawberry mousse, add your gelatine sheets into cold water and let them sit for about 15 mins. In the meantime, add your strawberries into a blend and blend until you have smooth puree, add them to pot with sugar and heat gently to about 65ºC, as soon as the sugar melted, take it off heat. Squeeze all the water out of the gelatine and add it into the warm strawberry puree. Stir well to make sure the gelatine has dissolved and incorporated into the mix properly. Let it cool to room temperature - it cannot be hot but stay liquid. Whip the cream half way, do not whip it too stiff or it will not combine with your puree well. The cream should be fluffy but still runny, not too stiff. Once you have the right consistency, incorporate the strawberry puree and mix gently into the cream.
Take your cake tin and fill the sides with grease/baking paper. Your sponge goes in first, followed by strawberry mousse. Spread the mousse on the sponge evenly and let it rest in the fridge.
Cut the remaining strawberries into slices and spread them on the top of the strawberry mousse. Once that is ready, prepare your quick jel according to the packet instructions and pour over the the top of the cake. Make sure the jelly is not too hot or your mousse will melt. Place your cake into fridge until the jelly on the top is set and enjoy.