One of the simplest, flakiest and tastiest cookie recipes to make.
The only “special” ingredient you need (because it’s a British recipe) is custard powder, which seems to be more readily available in the USA these days. The brand pictured here called “Birds” is the one you can find in many supermarkets and certainly online and is the best one to use.

Makes about 25 cookies.
5 oz butter, softened
6 oz superfine sugar (caster sugar)
1 large egg
1/2 tsp good vanilla extract
8 oz self-raising flour
4 oz Birds custard powder
4 oz white chocolate , chopped into small chunks

Heat the oven to 350 F
Line 2 to 3 baking sheets with baking parchment.
Put the butter and sugar in a food mixer and whizz until light and fluffy.
Add the egg and vanilla extract and mix well.
Sift together the flour and custard powder, then tip into the bowl and pulse to mix into a dough.
Scrape out the food mixer and work the chocolate in by hand.
Roll the dough into balls a little smaller than a walnut, then place on the baking sheets, a little apart to allow for spreading.
Press each cookie down lightly with your fingers.
Bake for 12 to 15 minutes until lightly golden.
Remove and cool on a wire rack.