2Preheat oven to 210C. Line a 23cm square pan with aluminium foil, so that the foil comes up over the sides (this allows you to lift out the slice).
4Place each pastry sheet on a baking tray lined with non-stick baking paper, then bake for 8-10 minutes or until golden brown. Set aside to cool.
5Once cool, place 1 pastry sheet, cooked-side up, in bottom of pan. (You may need to trim it slightly to fit.)
7Set slow cooker on high, I used a small one 2.4L
8Put the cornflour, sugar and custard powder in the slow cooker, and put the milk and vanilla mixture in and whisk until smooth,
9Then add cream, mix well.
10Place lid on slow cooker and let it cook for about 1 hour or until it thickens, stirring couple times in between.
11Add butter, stirring well to combine, then remove from heat and whisk in egg yolks, one at a time, until smooth.
13Pour into pastry-lined pan and set aside to cool slightly before placing other piece of pastry, cooked-side up, on top. Refrigerate overnight.
14Remove from pan, cut into squares and dust with icing sugar.
Submitted by Nancy Kleinig