Butter and pure maple syrup, for servingPreheat waffle iron.In a large bowl, whisk together the whole wheat pastry flour, all purpose flour, baking soda, salt, cinnamon, nutmeg, and brown sugar.In a small bowl (or large measuring cup), stir together the eggs, milk, Greek yogurt, and vanilla. Add all at once to the flour mixture and fold in gently, just until no streaks of flour remain. Do not over mix.Gently fold in the zucchini, lemon zest, and walnuts. Cook waffles according to your iron’s instructions. Serve immediately with butter and pure maple syrup.