Crumble! 1) Throw 400g rhubarb (chopped) into a greased baking dish & mix in 100g sugar. 2) In a bowl, rub 100g butter into 120g of flour and 70g of caster sugar until looks like breadcrumbs. Mix in 80g of porridge oats and spread evenly over the rhubarb. 3) Bake at 180 degrees for 40-odd minutes until starting to brown on top. 4) Serve. Vanilla ice-cream optional.