Preheat the oven to 180°C/gas mark 6.
Grease and line a 22cm square cake tin.
Cream the butter and sugar together until pale and fluffy. This can take a while by hand, so use a hand mixer or static cake mixer if possible, but not a food processor. Now add the banana – don’t worry if it looks a bit curdled, this is normal!
Beat the eggs in one by one and then add the cinnamon.
Now gently fold in the flour with a metal spoon until fully incorporated.
Turn your mixture into the cake tin, level off and bake for 30-35 minutes or until firm to the touch and the edges slightly coming away from the edges of the tin.
Once the cake is cooked, leave it to settle for five minutes in the tin and then invert onto a clean lined baking sheet. Remove the paper and leave while you make the frangipane.
Reduce the oven to 160°C/gas mark 4.
Place the almonds, butter, sugar, eggs and almond extract together in a bowl and beat until completely mixed.
Now carefully spread this over the top of your cake mix. Place the banana chips on top and then return to the oven for 15-20 minutes or until the frangipane is a light golden brown and set.