Pre heat over to 200 degrees
Rub butter into flour until mixture resembles fine breadcrumbs.
Stir in sugar, porridge oats and hazelnuts.
Place plums in a pan with 150ml (1/4pt) water, honey and orange rind.
Bring to boil and simmer for 15 minutes, uncovered, then transfer to an ovenproof dish and top with crumble mixture.
Bake for 35-40 minutes until golden.