1. Preheat the oven to 180°C, fan 160°C, gas 4. Grease and line 2 x 20cm sandwich tins with baking paper.
2. In a large bowl beat all of the sponge ingredients together, using a wooden spoon until the mixture is smooth and light.
3. Divide the mixture between the two tins, level and bake for 20 mins or until a skewer comes out clean. Leave to cool into the tins for five mins and then turn on a cooling rack.
4. To make the filling, beat the icing sugar and butter together with an electric whisk until pale and fluffy. Beat in the melted white chocolate. Starting at a slow speed, beat 100g of the strawberries into the butter mixture with the vanilla paste. When all ingredients are mixed together, increase the speed until the mixture is smooth, fluffy and a gorgeous pink colour.
5. Combine the remaining 175g strawberries with the mint. Place one of the sponges onto a cake stand, securing it with a little filling.
6. Using a piping bag, pipe large bulbs of the mixture around the edge of the cake, then cover the middle with the strawberries and mint. Top with the second sponge and pipe the rest of the mixture around the edge. Chill the cake for up to one hour to set.
7. Dip three of the remaining strawberries into the melted white chocolate cake covering and leave to set. Spoon the dark chocolate cake covering into a piping bag and pipe over the white-chocolate-covered strawberries. Place these in the centre of the cake with the other berries. Sprinkle with icing sugar and a dusting of gold lustre to serve.