Preheat the oven to 180°C / 350°F / Gas mark 4.
Line a baking tray with greaseproof paper and set aside.
In a bowl rub together the sugar, flour, baking powder and butter until it resembles breadcrumbs using your hands.
Add the oats, mix through the crumb mixture.
Pour the mix onto the baking tray and bake for 20 minutes.
Cut the rhubarb into 5cm lengths, place in a large pan with 50 ml of water, cover, bring to the boil and then reduce to a low simmer for 7 minutes, stirring until the rhubarb is soft.
Remove from the heat and drizzle in the runny honey.
Replace lid and let stand for 5 minutes.
Spoon the rhubarb into serving dishes, break the crumble topping and sprinkle over the top of the rhubarb.
Add a drizzle of honey and a spoonful of crème fraîche.