Mix the flour, sugar and baking powder in a bowl.
60 g plain flour (all-purpose flour), 35 g caster sugar (superfine sugar), ½ tsp baking powder
Melt the butter and mix it in.
25 g butter
Add the lime zest and then the milk and mix until smooth. Stir in the blueberries.
100 ml milk, zest of half a lime, two handfuls of blueberries
Pour the mixture into a small ceramic dish.
Mix the boiling water, jam and sugar together, then pour it over the cake mixture. It will look quite strange but do not fear! As the cake bakes it will come out from underneath the sauce, and the sauce will run to the bottom.
100 ml boiling water, 3 tbsp blueberry jam, 3 tbsp caster sugar (superfine sugar)
Bake at 180 degrees for approximately 30 minutes or until the cake is firm.