Prep: Line two 8 by 4 inch baking pans with parchment paper and preheat your oven to 325 F.
Make the batter: Using a handmixer with beaters or a stand mixer with a paddle attachment, beat eggs, vanilla, and sugar together in a large bowl until the mixture appears light and has increased slightly in volume.
3 egg, 350 grams cane sugar, 5 grams vanilla extract
Drizzle the oil into the batter and continue beating until the mixture is fully emulsified.
143 grams vegetable oil
Beat the sourdough discard and zucchini into the batter until no streaks of discard remain.
113 grams sourdough discard, 270 grams zucchini
Fold all the cinnamon, salt, baking soda, baking powder, cinnamon and a third of the flour in to the batter.
345 grams all-purpose flour, 6 grams salt, ¼ teaspoon baking soda, 8 grams cinnamon, 1 teaspoon baking powder
Continue folding the flour in gently. Add the walnuts in with the last addition of flour. Try not to leave any large streaks of flour or you’ll get powdery, dry spots in the loaf.
50 grams walnuts
Divide the batter evenly between the loaf pans. Whisk the cinnamon and sugar together. Sprinkle cinnamon sugar on top of the batter.
30 grams cane sugar, 1 teaspoon cinnamon
Bake: Bake for 60 to 65 minutes, or until a toothpick inserted in the center of the loaf comes out clean.
Enjoy: Allow the loaves to cool inside the pans on top of a wire rack for 20 minutes. Remove loaves from the pans, and allow to cool completely before serving.
Store: This bread is even better the day after it’s baked and keeps well in an airtight container at room temperature for up to 1 week.