Heat oven to 160C/140C fan/gas 3.
Line a muffin tin with 12 muffin cases.
With an electric whisk, whisk the butter,
250g of the sugar, eggs, flour, zest of
2 lemons and juice from 1 lemon until
just combined – don’t over-whisk. Divide
between the cases (they will be quite
full), then bake on a middle shelf for
30 mins, until a skewer poked in comes