Orange and sultana cheesecake slice

Method

1. Preheat oven to 180°C. Grease a 29 x 24cm slice tin with melted butter and line with baking paper.
2. For the base, combine flour and caster sugar in a large bowl. Using your fingertips, rub butter into flour until mixture resembles fine breadcrumbs. Add egg 
and mix until a dough forms. Press dough evenly over base 
of prepared tin. Refrigerate 
until ready to bake.
3. For the filling, whisk ½ cup milk 
and the custard powder in a jug. 
Set aside. Put remaining milk, butter, cream cheese, zest, juice and 
sugar in a medium saucepan over 
a medium heat. Whisk until cream cheese is melted and the mixture is well combined. Bring to the boil. Add custard mixture and whisk until well combined. Stir in the sultanas, then bring to the boil and cook for 2 minutes or until thickened. Remove from heat and transfer to a large bowl. Set aside to cool for 10 minutes.
4. Meanwhile, put eggwhites in 
the small bowl of an electric mixer and beat on high, using the paddle attachment, until frothy. With motor running, add extra sugar, 1 Tbsp 
at a time, beating well after each addition. Beat until a thick glossy meringue forms. Fold meringue 
into cream cheese mixture. Pour over slice base and spread evenly.
5. Whisk yolks and carefully brush 
over top of cream cheese mixture. Bake for 30-35 minutes or until 
set. Transfer tin to a wire rack to cool. Remove slice from tin and 
cut into fingers. Serve plain or dusted with icing sugar.