1. Pre-heat the oven to 190°C/Fan 170°C/Gas 5. Put the rhubarb in an ovenproof dish. Add the chopped stem ginger, ginger syrup and 100g sugar, then stir to mix.
2. Cover and cook in the oven for 25 minutes. Drain off about half the juices and reserve them.
3. Put the oats and flour in a bowl and rub in the butter. Stir in 75g sugar and the sunflower and poppy seeds. Sprinkle on top of the rhubarb in an even layer and bake for 45 minutes.
4. Serve hot with the reserved juices and custard or cream.