If you can’t find polenta, use a total
of 200g/8oz self-raising flour instead.
Heat oven to 180C/fan 160C/gas 4 and
make sure there’s a shelf ready in the middle
of the oven. Butter a rectangular baking tray
or small roasting tin, about 20cm x 30cm.
Cut out a sheet of baking paper a bit larger
than the tin, then push it in and smooth it
out with your hands so it sticks to the butter.
Snip into the corners with a pair of scissors
to get the paper to lie neatly.
Put all the cake ingredients and a pinch of
salt into a large bowl, then use electric beaters
to beat until creamy and smooth. Scoop into
the tin, then level the top. Spoon the lemon
curd over the batter in thick stripes. Use
the handle of the spoon to swirl the curd
into the cake – not too much or you won’t
see the swirls once it’s cooked. Bake for
about 35 mins or until golden and risen. It
should have shrunk away from the sides of
the tin ever so slightly and feel springy. Don’t
open the oven before 30 mins cooking is up.
Leave the cake in the tin for 10 mins or
until just cool enough to handle. Carefully lift
out of the tin and put it onto a cooling rack,
sat over a tray or something similar to catch
drips of drizzle. To make the drizzle, mix
4 tbsp sugar and the lemon juice together
and spoon over the cake. Toss the lemon
zest with the final 1 tbsp sugar and scatter
over the top. Let the cake cool completely,
then lift onto a board, peel away the sides
of the baking paper and cut the cake into
fingers. Will keep in an airtight tin for 3 days.