Place the rhubarb, 50 g caster sugar and two tablespoons of water in the slow cooker pot.
400 g rhubarb, 50 g golden caster sugar
Cook on high for 15 mins to soften it slightly.
Rub the butter into the flour, then stir in the sugar, egg and milk.
100 g self-raising flour, 50 g butter, 60 g golden caster sugar, 1 egg, 60 ml milk
Mix gently until combined.
Rub a little butter around the edges of the slow cooker pot to prevent sticking.
Then pour the toppping mixture on top of the rhubarb.
Cook on high for 90 mins to 2 hours until the topping is cooked through. Use a cloth (tea towel or kitchen towel) under the lid to stop drips from falling onto the top of the food.
Serve warm, with custard.