1 Mix the flour, hazelnuts, 125 g sugar and vanilla extract. Add the butter and rub in with your fingertips until the mixture has the consistency of breadcrumbs.
3 Wash, trim and peel the rhubarb and cut into small pieces. Sprinkle with the remaining sugar.
4 Put the rhubarb into the greased dish and sprinkle with the pearl sugar. Cover with the crumble mixture. Bake in a preheated oven (180°C with fan) for about 30 minutes.