The easiest sponge cake base. The simplest whipped cream filling, barely sweetened. The perfect lightly roasted blueberry flavouring, oozing purple juice. Need I say more?

Why is sponge cake called a sponge?
Sponge cake, as the name cleverly suggests, is supposed to soak up the filling/syrup/drizzle/jam/cream (though it will struggle with the last). Funny then how very non absorbent a lot of sponges are, especially the classic English Mary/Delia kinds.
What is the proper type of sponge cake then?
I’ve given up ranting about how the English sponge is not a sponge at all because it has butter in it; that the proper sponge mix is airy eggs with a puff of flour stirred into them; that sponge, genoise or viennoise is an adult affair involving separating eggs or at least beating them into triplicate over a bain-marie.
I’m simply becoming benign in my old age and don’t ferociously argue any more. They want to put butter in, beat it all together in one bowl, and call it a sponge – be it. Whatever - as long as it performs the spongy function above.
My idea of a perfect sponge dessert
So I came up with this wonderful dessert concept of lightly roasted blueberries oozing purple sweetness into the biscuit base. So far so lovely – but that would leave the top layer dry as a history handbook.
How about spreading the bluebs over the top then, thought I ingeniously, let them soak in and then sandwich the lot with whipped cream? The small snag was, of course, the impossibility of sandwiching two layers dripping with filling on the inside.
I did briefly consider multiple-decking the layers, each saturated with the blueberries, but whichever way I looked at it, the topmost crust would be dry.
It may not be a 'proper' sponge but it works
I gave up. Sponge, or what others call sponge. Standard two layers with the fruit and cream in the middle. Icing sugar on top. Sliced into thick wedges. Served with extra whipped cream.
Absolutely delicious.