1. Preheat the oven to 200°C/400°F/gas 6.
2. Put the rhubarb, ginger and orange zest in a hob proof baking dish and turn the heat on.
3. Sprinkle over around 4 tablespoons of the sugar and give the dish a good shake to mix all the flavours together.
4. Whilst the sugar starts to caramelize start making your crumble topping.
5. Rub the butter and flour together using your fingertips until it resembles coarse breadcrumbs.
6. Stir in the remaining sugar, toasted hazelnuts and cinnamon powder.
7. Sprinkle it generously all over the rhubarb and pop the dish in the oven.
8. Bake for around 40 minutes or until the crumble has started to turn golden brown. Serve hot with ice cold cream or warm custard.