In a separate bowl, whisk together flour, cinnamon, baking soda, creme of tartar, and salt until everything is well combined.
Add the dry mixture into the wet mixture and mix until well combined. (The batter will be thick.) Next, add zucchini to the batter and mix again until everything is completely mixed together.
In a separate small bowl, combine cinnamon, sugar, and creme of tartar to create the topping mixture.
Fill half of each loaf pan with the batter and sprinkle 2 tablespoons of the topping in each pan
Divide the remaining batter between the two pans and sprinkle the rest of the sugar mixture over the tops of each loaf.
Bake for about 45-50 minutes, or until a knife inserted into the center comes out clean.
Allow the bread to cool completely on a wire rack prior to serving.