Preheat the oven to 180 C / Gas 4. Grease a small (450g) loaf tin and line with baking parchment.
Cream the butter and sugar together in a bowl with a electric whisk until light and fluffy for about 4 to 5 minutes. Add vanilla, beaten eggs and mashed banana and mix well. Gently fold in baking powder and bicarb followed by the flour, a tablespoon at a time until well incorporated. Lightly stir through the chocolate and the almonds if using then finally add a little of the water if the mixture is too thick. Transfer the mixture to the prepared loaf tin.
Bake in the preheated oven for around 50 minutes until risen and golden, until a skewer inserted into the centre comes out clean. Remove from the oven and allow to cool in the tin for 10 minutes before transferring to a cooling rack to cool completely. Slice and serve.
For an extra sweetness or caramel twist. I sprinkle some brown sugar on the bottom of the tin before I spoon the mixture in so when you turn it out its lovely and caramely and adds a little extra crunch.
If you would like an extra bit of crunch, toast the almonds in a dry frying pan over a medium heat until fragrant, about 4 to 6 minutes, taking care to not let them burn. They are now ready to add to the cake mixture.