Preheat your oven to 180°C (Fan 160°C or Gas Mark 5).

Chop the rhubarb into 1-inch chunks, and peel and core the Conference pears before cutting them into similar-sized pieces. In a saucepan, combine the rhubarb, pears, 20g of unsalted butter, 50g of light brown sugar, and a tablespoon of cornflour. Cook over medium heat for about 5 minutes, stirring occasionally until the fruit softens and releases its juices.

In a mixing bowl, combine 200g of gluten-free self-raising flour and 100g of light brown sugar for the topping. Add 100g of cold unsalted butter, cut into cubes. Rub the butter into the flour mixture until it resembles coarse breadcrumbs.

Transfer the fruit filling into a crumble dish, spreading it evenly. Sprinkle the crumble topping over the fruit.

Bake for 35-40 minutes, watching for the topping to turn golden brown and the filling to bubble.

Let cool slightly before serving warm with custard, ice cream, or double cream.