The cake can be baked up to 3 days ahead as long
as it’s kept in a sealed tin.
Boil two of the oranges (whole) in water, with
the lid on the pan, for about 1 hour or until
squidgy. Drain and leave to cool.
Butter a springform cake tin, 23cm/9in wide
and 7cm/23⁄4in deep. Add 1-2 tablespoons of
polenta, tip the grains around until the tin is
coated, then knock out the excess. Set aside.
Whizz the flaked almonds to a grainy powder in
a food processor, then mix in a bowl with the
polenta and baking powder. Set aside.
Halve the cooked oranges and remove any
pips. Remove zest from the third orange. Whizz
the zest and the orange halves (with skin on) to a
smooth purée in the food processor. Set aside.
Preheat the oven to 180C/Gas 4/fan oven
160C. Using a mixer or electric beaters, beat
the eggs, yolks and sugar for a good 5-7 minutes until the batter looks like a very thick milkshake.
Quickly beat in the almond mixture, then the
purée until just blended. Pour the batter into the
tin, leaving at least 1.5cm/5⁄8in at the top.
Bake the cake in the middle of the oven. After
10 minutes, reduce the temperature to 150C/
Gas 2/fan oven 130C, bake for 30 minutes,
then reduce temperature to 140C/fan oven
120C for a further 30 minutes (if you have a gas
oven, cook at gas 4 for 10 minutes, then at gas
2 for 11⁄4 hours until done without reducing the
temperature further). The cake is ready when it
has risen, is golden-brown and the centre is just
firm – don’t panic that it still feels fragile.
Leave the cake to cool in its tin (it will sink a
little), then run a palette knife around the edge
before releasing the sides. Only attempt to
transfer it from the metal base to a decorative
plate or stand if you have a proper cake lifter.
Whisk the liqueur and marmalade into the
mascarpone. Serve the cake in thick wedges
with the mascarpone dolloped on top.