Granny Boyd's biscuits

I am in love with these biscuits. They are simple to make, quite ordinary to look at and yet there is something about them that is so delicious that I just cannot help baking and eating them. They come from Nigella's book How to be a Domestic Goddess and she describes them as 'dark, smoky and melting'. For some reason I googled them and now realise I am not alone in my appreciation.
She suggests eating them with vanilla ice cream, which is of course a great suggestion. Yesterday Jack and I made some with smarties on top (he loves to squish them right down into the dough - almost as much as he likes to eat the smarties) which are all gone. I've still got some of the originals left, though maybe not for long. So here's the recipe and yes they only have four ingredients (but they'll taste better than any of those recipes - you know the ones I mean)

Ingredients:

300g Self-Raising Flour
30g Cocoa Powder
250g Unsalted Butter (room temperature)
125g Caster Sugar

Steps:

1. Preheat the oven to 170 degrees C.
2. Sieve Flour and Cocoa Powder and set it aside.
3. Cream butter and sugar till light and pale in color.
4. Mix in flour mixture, it might look like it needs liquid, but keep working the ingredients in and it will form a dough.
5. Roll into walnut-sized balls and arrange these on the baking sheets.
6. Flatten these balls with the back of the fork.
7. Bake for 5mins at 170 degrees C and then turn the temperature down to 150 degrees C for a further 10-15mins.
8. The biscuits should feel firm on top although not hard. Remove from the oven and transfer to cool on wire rack, before storing in air-tight container.

As Jack would say, "thank you very much mummy, licious!"