- Preheat the oven to 160°C.
- Cake base: place the biscuits in the 500 ml chopper accessory from Braun’s MultiMix 3 Hand mixer HM 3135 and attach to the hand mixer. Start slow, mix gradually up to full speed to create a fine crumbly texture. Add the melted butter at medium speed to create a thicker texture.
- Press the crumbly mixture into the base of a 20 cm round tart mould.
- Place the filling ingredients except the egg whites into a large bowl and whisk using the whisk accessory. Start whisking at medium speed, gradually accelerating until the mixture is thick and smooth.
- Release the whisk accessory to rinse, re-attach and beat the egg whites in another bowl. Then fold into the filling mixture using a wooden spoon. Pour the mixture over the base and bake in the pre-heated oven for 50 - 60 minutes until golden.
- For the fruit purée, put the strawberries, raspberries, sugar and lemon juice into the chopper accessory, re-attach the hand mixer and mix. Pass the purée through a sieve and chill for 3 hours until ready to serve.