Basement (A kind of sponge cake):
There are many possibilities for the basement. For example, it is possible to prepare a proper genoise or use some cookies. In this case, I prepared a kind of sponge cake basement.
Separate the white/yellow parts of the eggs. Beat the white eggs untill solid. In another bowl, mix the yellow part of the eggs with the suggar. Add the some vanilla extract to give some nice taste and the baking powder. While mixing, add the flower little by little to get a nice composition. Add a little of the solid white eggs to the composition and mix it. Finally Add all the rest of the white solid eggs and mix kindly.
Bake in the cake pan you will use for the all cake at 180°C for about 15minutes (check with a knife to know the exact time).
In a mixer or a blender, put the fruits, 30g of sugar and the lemon juice. Mix this well untill you get a nice puree.
Let the gelatin sheets rest in cold water for about 10minutes. In a saucepan, heat up some fruit mix and add the gelatin sheets. Mix well untill the gelatin has dissolved and add the rest of fruits puree. Mix well and let cool down a little.
Whip the fresh cream untill it becomes solid (take care to not do butter!!! stop before it becomes yellowish).
(To easily whip the fresh cream, you can put the bowl and the fresh cream in the freezer for about 20minutes)
Add the fruits and gelatin puree to the whip cream and mix gently to get an homogeneous cream.
The best is to use a cake pan which side and bottom can be separated. Place the basement in the cake pan and cover with the mousse. Make it flatten on the top.
The idea here is to make your cake look nice (really?!?)... So, any good idea is probably possible.
I usually use a few spoon of strawberry jam (blueberry jam is also a good combination with the strawberry mousse) that I heat up in a pan with some water. Let it cool down a little and add the softened gelatin sheets.
Pour this preparation on your mousse (be sure that the mousse has been cooled down for 30min and that the preparation you pour on it is not hot or you will end up by creating some gelly stalactites in your mousse which can be artistic, but maybe not what you wanna do). Let your cake in the refrigerator for about 6hours so that your mousse get some nice consistency.