Grease a big round cake dish and cover the bottom with pineapple slices, blueberries and a little brown sugar (this is the short-cut version that was necessary due to a few small people milling around – apparently the top dollar version involves caramelizing the pineapple slices first).
For the sponge you beat everything together at once; 250g butter, 250g flour, 250g sugar and 3 – 4 eggs (depending on their size) 1 tsp baking powder. The butter needs to be pretty soft. Tip the sponge mix onto the fruit and bake.
I’ve never really done the upside-down cake so watching J and L put this together and has definitely inspired me to create a gluten free version – I’m also thinking this would work well with stone-fruit , have to see what’s at the market this weekend give it a go.