Aye, its from Just Like Mother Used to Make by Tom Norrington-Davies
For a 20.5cm baking tray ( roughly 12 slices )
butter for greasing
approx 250g shortcrust pastry
3 tbspn plum jam
2 large eggs separated
200g caster sugar
200g ground almonds
1 level tbspn Amaretto
25g flaked almonds
Grease a baking tray. Roll out pastry to line base and sides of baking tray. Prick all over with a fork and chill for 30 mins. (I love this sentence, it works on many levels 
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Preheat oven to 200c/400f/Gas 6 and if you have a large flat roasting tray ( bigger than tray with pastry in ) put it on top shelf of oven to get hot.
Roughly spread the jam all over the pastry base in baking tray.
Beat egg yolks and sugar together until plae and fluffy. Add ground almonds and Amaretto. Whisk egg whites to soft peaks and fold them into mix. Turn out onto pastry, to cover the jam. Sprinkle top with flaked almonds and place tray on hot roasting tray. Bake for around 30-40 mins intil almonds golden brown.
Allow to cool in baking tray for 10 mins before turning out onto wire rack. Cut into slices when completely cooled.