Preheat oven to 180C/160C fan assisted. Grease standard dinner plate with butter.
Add flour and sugar to big bowl and rub butter and cooking fat into the mixture until it's like a breadcrumb look and texture.
Create a well in the middle and add cold water gradually. Each flour is different and will need different amounts of water. Ensure pastry comes together and not too wet. Bring together in a ball and cut into four. Put one ball aside for top of cake. Rest of pastry is enough to make a second cake.
Flour surface, rolling pin and pastry then roll out pastry thinly to fit plate. When ready, roll back onto rolling pin and then roll forward onto plate trimming all the edges and patching any holes if necessary.
Wash, peel, core and slice apples but not too thick because they haven't been stewed in advance. Spread evenly on top of pastry and top with caster sugar. Leave gap on outsides and then brush milk around outsides to help with layers joining later.
Repeat pastry process with ball set aside earlier and put on top. Press down on outsides and trim all edges. Then dip fork into water and crinkle pastry with back of fork on outsides. Dip fork into water and pierce 4-6 holes on top to allow steam to escape during cooking.
Place in oven for about 40 minutes or until golden brown. Allow to cool on a wire rack before decorating with granulated sugar. Enjoy on its own or with custard or fresh cream.
