Rub a baking dish with butter to lightly grease it (I used an 8x8in (20x20cm), roughly 2 quart dish).
Chop bread into chunks around 1-1 ½in/3-4cm across. Put them in the dish.
Mix together the eggs, milk, cream, vanilla, cinnamon, nutmeg and ginger and pour over the bread. Toss any pieces that aren't covered in the custard and tuck them in so they form one layer, as far as possible. Cover and refrigerate overnight. If you don't manage to prepare ahead, you can also do it the same day, but I recommend letting it sit at least 20 - 30 minutes to let the bread soak a bit.
When ready to bake, preheat oven to 400F/190C.
Peel and slice the banana and tuck the slices in between the bread. Crumble the pecans and mix with the sugar and sprinkle over the top.
Bake for around 20 minutes until it's gently crisp on the top and soft but cooked underneath like bread pudding, or another 5-10mins more for a slightly dryer, crisper texture.