Strawberry buttersponge with mascarpone mousse

Instructions

1. To make the mascarpone mousse filling, bring the milk, vanilla and salt to the boil in a small saucepan, then remove from the heat. Squeeze out the gelatine leaves and add to the hot milk. Place the white chocolate into a medium bowl and pour over the milk mixture. Whisk to melt the chocolate, then cool to 25˚C. Beat the mascarpone and cream to medium peaks, refrigerate until needed. Gently fold the cooled chocolate mixture and chilled cream together, then use as needed.
   
2. To make the strawberry sherbet dust, in a small food processor, blitz the ingredients to a powder.
   
3. Preheat the oven to 140°C (fan-forced). Lightly spray a 40 cm × 30 cm × 2 cm deep tin with cooking oil spray and line with one sheet of baking paper. Spray the baking paper lightly.
   
4. Heat the butter and lemon zest in a small saucepan over medium-high heat. Cook until the butter is pale brown and the lemon zest sizzles. Pour into a large mixing bowl with the milk, whisking to combine. Whisk in the egg yolks.
   
5. In a second medium bowl, combine the flour, baking powder and salt and set aside.
   
6. In the bowl of a stand mixer with the whisk attached, combine the egg whites, sugar and cream of tartar. Beat on high speed for 3-4 minutes, until stiff peaks form.
   
7. While the egg whites are beating, sift the flour mixture over the egg yolk mixture, then whisk to a smooth, thick paste. When the meringue is ready, fold it into the flour and egg mixture in thirds, then transfer the batter to the prepared tin. Bake for 15-18 minutes, or until the cake is pale gold, then remove from the oven and invert onto a greased wire rack and allow to cool.
   
8. While the cake cools, lightly spray a 20 cm round x 7.5 cm deep cake tin with spray oil, then line with baking paper. Invert the cake onto a work surface and remove the baking paper, then use a 19 cm diameter plate or pot lid to carefully cut two sponge circles from the cooled cake. Divide the strawberry jam between the two sponge cakes, spreading to the edges of the cake.
   
9. To assemble, place one round sponge cake into the lined cake tin, jam-side up. Pour in half of the mascarpone mousse mixture, then smooth out and tap lightly. Place the strawberries in concentric circles – “top to tail”. Pour over the remaining mascarpone mousse and gently shake to ensure it fills in the gaps of the strawberries. Flip the second sponge circle on top, jam-side down.
   
10. Cover with plastic wrap, then sit a flat plate (or tart tin base) on top with a weight on top (like a block of butter). Chill for at least 4 hours before unmoulding.
    
11. Just before serving, peel the plastic wrap back to expose the cake. Cut into wedges to serve. Sprinkle with strawberry sherbet dust to serve.