Heat oven to 180C/fan 160C/gas 4. Line
a 900g/2lb loaf tin with non-stick baking
paper, using a little oil to make it stick. Put
the dates into a small pan with 200ml
boiling water and simmer for 5 mins. Drain
the liquid into a jug, then put the dates into a
food processor. Add the bananas and 100ml
of the date liquid and whizz until smooth.
Mix the nuts, dried fruit, polenta, spice and
baking powder in a bowl, then add the date
purée and rum, and stir until combined.
Whisk the egg whites to soft peaks and
fold into the cake mix. Tip into the tin (it will
be quite full), then top with the remaining
pecans and the banana chips and sugar,
if using. Bake for 1 hr until golden and
crusty and a skewer comes out clean.
Cool completely before cutting into slices.