Preheat the oven to 180C/gas 4/
fan 160C. Butter and line the base
of a 20cm round cake tin.
Put the butter, sugar, eggs, flour,
baking powder, cinnamon and
milk into a bowl. Beat with a
wooden spoon for 2-3 minutes,
or with an electric hand mixer for
1-2 minutes, until light and fluffy.
Tip three quarters of the mixture
into the tin, spread it level, then
spoon the Nutella on in four blobs.
Top with the remaining mixture,
swirl a few times with a skewer,
then smooth to cover the Nutella.
Sprinkle with the nuts. Bake for 1
hour to 1 hour 10 minutes, until risen,
nicely browned, feels firm to touch
and springs back when lightly
pressed (cover with foil if it starts to
brown too quickly). Cool in the tin
for 10 minutes, then turn out, peel
off the paper and cool on a wire
rack. Wrap tightly in double thick
foil to keep fresh for up to a week.