Preheat the oven to 200 C / Gas 6. Lightly grease the bottom of the cake tin with butter.
In a medium bowl, cream together the butter, the 150g sugar and 1 egg until smooth. Blend in the flour to form a dough. You may have to knead by hand at the end.
Roll the pastry out and place into tin. Pastry may be a little too short, so may need to press it into the tin by hand. Cover the bottom and sides of the tin.
For the egg custard filling: in a bowl, mix together the 4 eggs and 100g sugar and add vanilla pod or extract. Gradually stir in the cold milk to fully incorporate. Pour mixture over the pastry base. Sprinkle over the nutmeg.
Place in the oven until a sharp knife inserted near the centre comes out clean, about 45 minutes. Once egg custard is set bring out from the oven and cool. Enjoy!