Preheat the oven to 180°C.
Mix pears, lemon juice, and sugar in a bowl.
Bake covered pears for 10 minutes, then add apples and bake for another 30 minutes.
Crush the cooked fruit with a fork, cool, and fold in blackberries.
Rub flours, butter, and brown sugar into breadcrumbs.
Bake the crumble mixture on lined paper for 15 minutes until golden.
Melt sugar and nuts in a pan for 5 minutes until coated and golden.
Cool the nuts on greaseproof paper and crush them into a coarse powder.
Whisk cream, yoghurt, mascarpone, sugar, and spices to soft peaks.
Layer crumble, fruit, cream, and nuts into glasses twice.
Serve immediately or chill and add nuts just before serving.