Preheat oven to 350°F. Spray one 9 X5 loaf pan (See note) with oil and dust with flour.
Grate the zucchini and measure 3 cups, unpacked. Chop the pistachios coarsely.
Sift the flour, cinnamon, salt, and baking powder together. Mix in the oats and chopped pistachios.
In another bowl beat the eggs well. Add the oil and sugar and beat until the mix feels thickened and increases in volume slightly. Add half the dry mix to this and fold in gently. Add the grated zucchini and fold in. Finally, fold in the remaining flour mix.
Make the topping (optional)
Mix in the finely chopped pistachios, sugar, and the rolled oats.
Transfer the batter to the prepared pans and spread the topping evenly on top.
Bake at 350 °F for about 60 minutes or until a toothpick inserted in the center of the loaf comes out dry.
Cool in pan for 5 minutes. Transfer to a cooling rack and cool completely before slicing.
2 smaller loves of size 81/2 X 4 ½
If making smaller loaves the cooking times will have to be lowered.
Ovens vary, check at around 50 minutes mark to prevent overcooking.