[food] rhubarb & ginger upside-down cake

Gingerbread-apple upside-down cake, except:

Topping
50g butter
100g muscovado sugar
splash of ginger cordial
Some rhubarb

Melt butter and sugar together. Add a splash of cordial and the rhubarb, cut into ~2" chunks. Simmer gently until the rhubarb has started softening up, remove from heat, proceed as with previous recipe.

(I used... six or so stalks? I just pulled Some off the plants.)