Make the shortbread first. Set the oven at 160C/gas mark 4. You will need
a 20cm shallow tart tin or sponge tin that is nonstick or one that is lined with baking parchment.
Toast 75g of skinned hazelnuts in a dry, shallow pan, moving them regularly around the pan so they colour evenly, reserve a handful of them, then grind the rest to a fine powder in a food processor.
Using a food mixer with a paddle attachment, beat 125g of butter and 50g of icing sugar until soft and fluffy. Stir in a pinch of sea salt and 75g of plain flour. Add the ground nuts and a drop or two of vanilla extract.
Lightly flour your hands, bring the dough into a ball, then press into the lined tin. Take the dough right to the edge of the tin. Bake for 25 minutes until pale gold in colour. Remove the shortbread from the oven and leave to cool.
Whip 250ml of double cream until it is thick enough to hold a shape. Take care not to overwhip it. The cream should stand in soft mounds, not stiff peaks.
Peel 600g of bananas (about 5) and slice them thickly (about 1cm). Place a wide, shallow, nonstick pan over a moderate heat, then sprinkle in 50g of caster sugar and add the sliced bananas. Watch carefully as the sugar starts to melt. As soon as the syrup is the colour of golden syrup remove from the heat.
Spoon the cream over the shortbread, leaving a rim of bare cake around the edges. As soon as the bananas are cool, tip them on to the cream and scatter over the remaining toasted hazelnuts. Serves 4
When pushing the dough into the tin, press down firmly but gently, making sure not to contact the mixture. It needs to be fragile to the touch.
Make certain that the bananas are cool before you put them on the shortcake, otherwise they will melt the cream.
Follow Nigel on Instagram @NigelSlater