200g caster sugar
150g butter
1 large egg
1 teaspoon vanilla
200g plain flour
2 teaspoons baking powder
zest of 1 lemon and 1 orange
Allow butter to soften for an hour. Mix together the butter and sugar until combined (doesn't need to be as creamed as for a Victoria sponge, just well combined).
Mix the egg and vanilla together and add those to butter/sugar and mix thoroughly.
Sift together the flour and baking powder. Add those to the mix and stir well.
Add the zest and mix thoroughly.
Turn the dough onto a piece of greaseproof paper, shape into a log and put into the fridge for an hour to harden up a little. (Can be frozen at this stage too).
Slice the dough into rounds, put onto baking tray and bake for 7 minutes (it usually really takes them about 12 I find) at 180 degrees C.
Alternatives to the orange and lemon are to replace about 25g or so of the flour with cocoa powder and add some chocolate chips to the batter instead of the zest; or to use some dessicated coconut; or just have them plain. (I think there was another option in the book but I didn't have time to type it up last night when I made a batch, but it jogged my memory for the quantities and I had promised ages ago!).
The dough lasts very well for at least 8 months in the freezer according to my slatternly ways (book says 1 month) and at least a week in the fridge (book says a week - I've tended to freeze if it would be longer than that).