Rhubarb crumble with walnuts

1) Heat oven to 200°C/400°F .
2) Toss the rhubarb and caster sugar together and place in the baking dish.
3) Make the crumble by rubbing the flour and butter together between your fingertips until it resembles fine breadcrumbs. You could do this in a food processor. 
4) Add the muscovado sugar and the nuts and stir well.
5) Press the rhubarb well down into the baking dish and top with the crumble mix. Press down gently.
6) Bake for 35 – 40 minutes, until golden brown.
7) Leave to rest for 10 minutes before serving warm with the cream.