Heat the oven to 190c/170 fan/ gas mark 5
Place the pears in a pan and add the maple syrup, brown sugar and star anise. Cook for 10 minutes until the pears start to soften. Add the blackberries, vanilla and remove from the heat.
Place the flour, butter, oats, demerara sugar, and a pinch of salt into a large bowl and rub together until the mixture looks like breadcrumbs. Stir in the hazelnuts and sugar and stir to combine.
Sprinkle the crumble over the cooked fruit and then bake for 20-25 minutes - until golden on top and the fruit is bubbling.