• Preheat the oven to 200˚C (400˚F / 180°C Fan).

Rhubarb Filling

• Chop the rhubarb into 2.5cm (1in) pieces and place them in a bowl.
  500 g rhubarb
• Sprinkle the white sugar, ground ginger and cornflour all over and mix thoroughly using your hands. Place in the baking dish and set aside.
  60 g white sugar, ¼ tsp ground ginger, 1 tsp cornflour

The Crumble

• If you have a large chopper or food processor, place the cold butter and flour and pulse until the mixture resembles wet sand, then tip into a large bowl. Otherwise, chop up the butter into little cubes and rub into the flour using your fingertips. Don't knead. Do all this in a large bowl.
  150 g cold salted butter, 200 g plain flour
• Add the demerara and white sugar to the flour/butter mix and using your fingertips, mix it all in. Do not overwork, keep it light, crumbly and airy.
  60 g demerara sugar, 30 g white sugar

Assembly

• Sprinkle the crumble all over the rhubarb in an even layer. Don't press it down. This will leave the crumble light and crispy.
• Bake for about 35-45 minutes, until the top is a golden brown, looks crispy and the sides are bubbling a little with the rhubarb. I like mine brown and crispy, so I tend to go for 45 minutes. It's a matter of taste.
• Take it out of the oven and let it rest for 5 minutes, then serve as mentioned above.
  custard

Still great, heated up the next day!