Strawberry sponge cake:

1. Pre-heat the oven to 325F and line a 9" round cake pan with parchment paper (do not add butter or baking spray)
2. Blitz freeze dried strawberries in a food processor until they turn into a powder. Make sure you don't do this far in advance, because the crushed strawberries become sticky and moist with time, making them hard to mix into the batter
3. Add the eggs, sugar and vanilla to a bowl. Whisk on high speed for 3-4 minutes until the mixture triples in volume and becomes very light, fluffy and ribbony in texture
4. Sift in the flour, baking powder and salt. Use a rubber spatula to very slowly and very gently fold in the dry ingredients until they are almost combined, but not all the way
5. Add the crushed freeze dried strawberries, and very slowly and gently fold them in until just combined. Take care not to overmix or knock out the air from the batter, as that will cause the cake to deflate and turn out dense
6. Transfer the batter to the 9" pan, and bake in the pre-heated oven for ~14 minutes until a toothpick inserted in the center comes out with some light crumbs
7. Let the cake fully cool down

Ice cream mousses:

1. To save time, I recommend preparing the 3 mousses in tandem. Make sure the 3 ice creams are fully melted at room temperature, and measure them out into 3 large bowls
2. Take 3 smaller bowls for the gelatin. Add 5 tbsp cold water into each bowl, then add 5 tsp powdered gelatin into each bowl. Stir each bowl so the gelatin mixes with the water. It will still be grainy, that's ok. Place the bowls in the fridge for ~10 minutes until the gelatin firms up (meaning it has "bloomed")
3. Once the gelatin has firmed up, it is time to heat and dissolve it. Working with one bowl of gelatin at a time, microwave for 15-20 seconds until the mixture warms up, and stir to dissolve the gelatin. If it still looks lumpy, microwave for another 10-15 seconds and stir again until dissolved. Repeat with all 3 bowls of gelatin
4. Pour one small bowl of the dissolved gelatin into each bowl of ice cream - I recommend using a fine mesh sieve to make sure no little lumps of gelatin get into the ice cream. Stir to combine the gelatin with the ice creams

Assembly:

1. Place the cooled down cake on a cake stand. Wrap the cake with an acetate collar so that it is tight with no gaps, but not so tight that the cake is getting deformed. Also make sure the acetate collar is straight, then secure it with tape. This acetate will hold the mousse layers
2. Gently pour the chocolate ice cream mousse into the acetate collar on top of the cake. Place the cake in the fridge for 1-2 hours until the mousse has set. Leave the other mousses outside at room temperature in the meanwhile
3. When the chocolate mousse has set, gently pour on the strawberry mousse layer. I recommend doing this with a spoon and testing out with a little bit first to make sure the mousse layers don't start to mix up. Place back in the fridge for ~1-2 hours until the strawberry mousse layer has set
4. Repeat with the vanilla mousse layer. Then place the cake in the fridge overnight until it has fully set

Decoration:

1. Prepare the chocolate ganache by adding the cream and chocolate to a microwave-safe bowl, and microwaving in 20 second increments, stirring in between, until the chocolate melts and a smooth ganache forms. Let it cool down for 10 minutes
2. Once the cake has set, carefully remove the acetate collar. You can use a knife or offset spatula to smooth out the edges of the cake if needed
3. Carefully spread a layer of the chocolate ganache on top of the cake - I like to make a swirl with an offset spatula
4. Decorate with strawberries
5. Serve & enjoy! Make sure to keep the cake refrigerated and don't leave it out for too long

Video tutorial: