Preheat oven to 350 degrees. Grate zucchini and squeeze out any extra liquid with a towel. Set aside. In a medium mixing bowl, combine flour, baking soda, baking powder, cinnamon, and salt together. In a separate large mixing bowl, add eggs, oil, applesauce, Greek yogurt, vanilla, and maple syrup. Whisk together until well combined. Stir in the grated zucchini. Pour the flour mixture into the wet mixture. Mix until just combined.

To make the crumb topping and center, mix together the brown sugar, flour cinnamon and pinch of salt. Add cubed butter, and using a pastry cutter or fork, cut the butter into the sugar and flour. Continue to do this until it fully mixed in and resembles sand.

Grease or use parchment paper liner in a 9.5x 5.5 metal loaf pan. Pour half of the zucchini bread batter onto the pan. Sprinkle half of the crumb mixture over the batter evenly. Top with remaining zucchini batter, and spread out evenly if needed. Sprinkle remaining crumb topping. Bake for 50-60minutes, just until the bread has cooked through and a tooth pick comes out clean. Let cool and enjoy