Banana cake was one of the first recipes I adapted and perfected to my own tastes, back when I opened my little sandwich shop in Donny town centre in 2007.
The addition of the dark muscovado sugar was a chance I took, when I ran out of caster sugar - and it became my secret ingredient from then on. It elevates it from a decent cake, to a really bloody luvvley cake. By all means use whatever
These brownies are very rich and fudgy. If you prefer them more of a cakey texture, just add an extra quarter teaspoon of baking powder, and bake for 5-10 more minutes.
As always, the better quality ingredients you use, the better the outcome, so please go for real butter and decent quality chocolate if you can. However, cheap supermarket chocolate and baking blocks such as Stork still give a thoroughly decent brownie.