Preparation Steps

• Heat the oven to 350°F (175°C). Lightly grease a standard 9x5-inch loaf pan and line the bottom with parchment for easier removal.
• Make the streusel: stir the flour, brown sugar, and cinnamon in a small bowl. Pour in the melted butter and toss with a fork until large crumbs form. Set aside while you prepare the batter so the butter firms a little.
• In a medium bowl combine the flour, baking soda, pumpkin pie spice, cinnamon, and salt. Whisk to fully distribute the leavening and spices.
• In a separate large bowl whisk the brown and granulated sugars with the oil until smooth. Add the egg, pumpkin puree, and vanilla, and whisk until the mixture is glossy and uniform.
• Fold the shredded zucchini into the pumpkin mixture with a rubber spatula so it’s evenly dispersed. Squeeze any excess moisture from the zucchini before adding to avoid a wet batter.
• Add the dry ingredients to the wet mixture in two additions, folding gently after each addition until just combined. Do not overmix; a few streaks of flour are fine. Fold in the chopped nuts if using.
• Spoon the batter into the prepared loaf pan and smooth the top. Sprinkle the streusel evenly over the batter, pressing lightly so it adheres but remains crumbly.
• Bake on the center rack for 60–70 minutes, rotating the pan halfway through baking so it bakes evenly. The loaf is done when a toothpick inserted near the center comes out with only a few moist crumbs attached.
• Remove from the oven and let the bread cool in the pan on a wire rack for about 15 minutes. Run a thin knife around the edges, lift out using the parchment, and cool completely on the rack before slicing so the crumb sets.
• Store cooled bread wrapped tightly at room temperature for up to 3 days, or refrigerate for up to 5 days. Warm slices briefly before serving if desired.