Preheat oven to 190°C. Cream butter and sugar in a bowl until it turns a light colour. Gradually add beaten eggs one at a time. Mash banana on a plate with vanilla essence/extract and sprinkle with ground ginger and/or cinnamon and mix through. Mix bicarb soda in a cup with the milk. Add mashed banana mixture into creamed butter and sugar and mix until combined. Add milk and flour to banana mixture and combine. Pour into a greased and lined loaf tin and bake for 45 minutes or until skewer comes back clean. Cool on cake rack.