Preheat the oven to 350f and set the rack to the middle level. Spray or grease a 9x5 inch loaf pan and set aside.
In a small bowl, combine 1/4 cup of sugar and 1 tablespoon of cinnamon for the filling and set aside.
In a large bowl combine the flour, baking soda, baking powder, salt, cinnamon, and sugar.
In a separate large bowl whisk together the eggs, Greek yogurt, vanilla, and melted butter, then add the zucchini and whisk to combine.
Add the dry ingredients to the wet and mix just until combined taking care to not overmix.
Pour 1/3 of the zucchini bread batter into the loaf pan and top with 1/2 the filling. Add another 1/3 of the batter and top with the remaining filling, saving 1 teaspoon of filling for topping the frosting later in the recipe, if desired. Add the remaining 1/3 of batter to the loaf pan and give a gentle shake to distribute the batter evenly.
Place in the oven and bake for 45-55 minutes or until a toothpick inserted in the center comes out clean.
Allow the zucchini bread to cool in the pan on a wire rack for at least 1 hour prior to frosting.