Cut the stems of rhubarb into 1" chunks and place into an oven-proof dish. Spoon over the caster sugar and mix well to combine then set aside.
Make the crumble topping by first placing the flour, sugar and cold cubes of butter into a large mixing bowl. Rub together gently to form a breadcrumb like consistency.
Spoon the crumble over the rhubarb ensuring an even layer. Place in a pre-heated oven at 180CFan and bake for 40 minutes until the top is golden brown.
Serve with custard, or ice cream.
This is a simple traditional rhubarb crumble, however if you wish you can add 1tsp of ground ginger to the rhubarb. Alternatively some finely diced stem ginger and 1 tbsp ginger syrup also makes a great pairing with the sour rhubarb.Fruit crumble is a versatile dish. Feel free to substitute rhubarb with the fruits of your choosing. Apple and cinnamon, mixed berry or stone fruit crumbles all work really well with a crumble topping.