Heat oven to 370°F.
Line two x 1-pound loaf tins with baking parchment.
In a large bowl, mix together flour, baking powder, salt, cinnamon, lemon zest & sugar.
In a jug beat the eggs, melted butter and milk. Mash the bananas and fold all into dry ingredient mix. Then fold in the dark chocolate drops and about 2/3 of the walnut pieces.
Transfer the mixture into the lined tin.
Sprinkle the remaining walnuts on top.
Bake for 30-35 minutes until the bread is golden and springy to the touch.
Leave in the tin for about 10 minutes before turning out on a wire rack to cool.