Nigella 'How to Eat' p.46 says
120g self-raising flour (Nigella says plain's OK.)
90g butter, cold and diced into 1cm cubes
3 table spoons light muscavado sugar (I use the really dark brown stuff.)
3 table spoons vanilla sugar (that's way too posh for this kitchen, so I use caster sugar)
To which I add a handful of jumbo rolled oats. Nuts can be nice too. Sultanas ....
Crumble away. Do what you do with your fruity bits. Add a bit of sugar and water? That all depends on what it is and how tart the fruit is -very in the case of my Mum's windfall Bramleys just now.
Gas mark 5/ 190C for 25-35 mins.
Butter room temp or cold? I'm pretty relaxed on that, though never really soft.
My Mum just does the good ol' 3:2:1 method flour:sugar:butter and my Dad has been eating away merrily for forty years on her crumbles. No complints from that end of the table. She says it can be very crumbly or pleasingly shortbready depending on the whim of the cook. Very sweet or not so.
I like Nigella, but the grams thing and then tablespoons.... SI Units for cooking needed here methinks. Also, I have 3 different sizes of tablespoons and that doesn't seem to have messed up the crumble ever. The dark brown sugar is nice though.
So there we are. Anyone else have anything to say on this topic?