I don't know how to count in cups or grammes, but this is the way I do it:
8 ounces plain flour (ie with no raising agent) - an ounce of flour is about a tablespoon
6 ounces butter - this is about three-quarters of a pack
2 ounces caster (ie quite finely ground) sugar - a bit less than 2 tablespoons, since sugar is heavier than flour
Put all in bowl together and rub in till it sticks together. Using a mixer is fine. Press into Swiss roll tin. Cook at about 170 C (medium heat) for about 25 minutes or till pale golden (see picture).
4 ounces butter or margerine
4 ounces sugar
a small tin of sweetened condensed milk , eg Nestle's. I don't have the tin any more but looking at a tin of beans in my cupboard, I'd say the tin might have been about 200 grammes. Yes, I know this is metric, but that's all I have to consult. I use the smallest tin you can get, unless I do a double quantity, in which case I use the bigger size.
Put all this in non-stick saucepan over lowish heat. Stir continuously for ten minutes or so. Stop when the toffee mixture is fairly solid, rather like a very thick sauce. Actually, very thick custard made with custard powder would be a better description, though useless for those who've never made this. The mixture should come away from the sides of the pan for a few seconds before collapsing back into goo. If you make it too thin, it'll flow out of the middle of the shortbread when you cut it. If you make it too thick, it'll cool to a rather dry consistency. Experience is the key. Sorry to be so helpful.
Pour on top of the shortbread. You don't have to leave this to cool first.
Good quality melted chocolate - maybe 10 ounces (ie a good big slab). Pour this on top of the toffee.
This is possibly not a very healthy food item. Maybe you should just look at the picture.