Preheat oven to 350°F.
In a large bowl combine the flour, sugar, baking powder, baking soda, cinnamon and salt.
In a small bowl, whisk together the milk, oil, eggs and lemon zest and add to the flour mixture along with the grated zucchini and walnuts. Stir by hand just until combined. Don’t worry about getting all the lumps out.
Pour into an 8” x 4” loaf pan that has been sprayed with nonstick spray and bake for 1 hour, until golden and springy to the touch. Cool in the pan on a wire rack. Makes 1 loaf, with about 16 slices.