Step 1
Preheat the oven to 175°C (350°F) and lightly grease a 23x33cm (9x13-inch) baking dish.
Step 2
In a bowl, mix the flour, cinnamon, baking soda, salt, and baking powder. In a separate bowl, combine the zucchini, sugar, vegetable oil, eggs, and vanilla. Add the flour mixture to the zucchini mixture and stir until just combined. Stir in the walnuts, then pour the batter into the prepared pan.
Step 3
Bake in the preheated oven for about 45 minutes, or until a toothpick inserted in the center comes out clean.