Not as good as Mamgu's but very tasty anyway!
8oz SR flour, 4oz butter - rub butter into flour as if making pastry. Add 3oz caster sugar and 3oz sultanas, and a dash of mixed spice (not traditional) then mix in one large egg and bring it all together to make a dough - add a splash of milk if needed. Roll out to 5mm thickness and cut out rounds (approx 2" diameter). Heat up a griddle and wipe it lightly with butter - not too much. Don't get it too ferocious hot. Cook the welshcakes on the griddle on a GENTLE heat until lightly brown on the underneath, and semi-cooked. Flip over and brown the other side. The only way I can tell if they are cooked through is by poking them gently, to see if they've firmed up. It takes a while to cook them, as you have to be gentle. Eat them quickly, just as they are, while they are still warm.
NB: The trick is to get them lightly brown yet cooked all the way through. If the griddle is too hot, they get way too brown before being cooked. My ones in the photo are too brown, hence not as good as Mamgu's - but she's Welsh and has been doing it for years, and I'm step-daughter so not Welsh. You have to be born to it.