America's Test Kitchen Zucchini Bread Recipe: Moist Crumb With Walnut Swirls

This America's Test Kitchen zucchini bread recipe delivers the perfect balance of moist crumb and rich walnut swirls that keep slices tender for days. 💛 The secret lies in grated zucchini (not pureed) and a precise ratio of brown sugar to butter, which creates that signature dense yet tender texture.

I've tested countless variations, and this method consistently produces bread that's so good, even zucchini skeptics ask for seconds.

What sets this recipe apart is the walnut swirl—chopped walnuts folded into the batter create pockets of nutty flavor that contrast beautifully with the sweet crumb.

The bread bakes up with a golden crust and a slightly domed top, thanks to a simple technique of baking in a loaf pan without greasing it. This ensures crisp edges while keeping the interior perfectly moist.

By the time it emerges from the oven, you'll have a loaf that's fragrant, tender, and packed with that signature zucchini flavor without being overly sweet. The walnut swirls add texture and richness, making each slice satisfyingly hearty.

This is the kind of zucchini bread that earns a place on your breakfast table or as an afternoon treat.

Perfect for gifting, holiday baking, or satisfying cravings, this recipe delivers restaurant-quality results at home. The bread stays fresh for days when stored properly, making it ideal for meal prep or sharing with neighbors. Let's get baking!

Ingredients for america's test kitchen zucchini bread

Grated zucchini and walnuts transform simple pantry staples into America's Test Kitchen's signature zucchini bread.

The zucchini is non-negotiable—grate it yourself (the boxed kind is too wet) and squeeze out excess moisture. Freshly grated zucchini retains its texture better than pre-shredded. For walnuts, Costco or Trader Joe's offer the best prices, and toasting them for 5 minutes before chopping adds depth. The butter should be at room temperature—this ensures proper creaming with the sugars. If your kitchen runs warm, microwave it for 40 seconds to just melt it. The flour? King Arthur or Gold Medal brands are my go-to for consistent baking results.

No walnuts? Pecans or almonds work in a pinch, but the flavor won't be identical. Substitute the milk with almond milk for a dairy-free version, though the texture may be slightly denser. For the sugars, you can use all brown sugar if you prefer a deeper molasses flavor, but the combination of light brown and granulated creates that perfect balance of moisture and sweetness. If you don't have vanilla extract, imitation vanilla will work, though it lacks the complexity. The baking soda is essential—don't swap it for baking powder, or your bread will taste flat.

This bread stays fresh for 4-5 days when wrapped tightly in plastic at room temperature, or up to 2 weeks in the fridge. For longer storage, freeze slices wrapped individually for up to 3 months. I always bake an extra loaf—it's perfect for gifting or stashing in the freezer for lazy mornings. The walnut swirls add richness, so don't skip them. If you're feeling ambitious, brush the top with a little milk before baking for an extra golden crust.

Step-by-step instructions for america's test kitchen zucchini bread

Here's the method that guarantees a perfectly moist crumb with those signature walnut swirls.

Start by grating the 2 whole medium zucchini using the large holes of a box grater. Place the grated zucchini in a clean kitchen towel and gently squeeze out all excess moisture - this prevents a gummy texture. In a medium bowl, whisk together the 2.5 cups all-purpose flour, 2 teaspoons baking soda, 2 teaspoons ground cinnamon, and 0.5 teaspoon salt. Set aside for now.

I always toast the 1.5 cups chopped walnuts first while I work - spread them on a baking sheet and bake at 350°F for 8-10 minutes until fragrant. This enhances their flavor dramatically. Let them cool completely before using. The dry ingredients will stay ready for the creaming step while you handle the zucchini.

In a stand mixer fitted with the paddle attachment, beat the 1 cup unsalted butter (at room temperature) with the 1 cup light brown sugar and 0.5 cup granulated sugar on medium speed for 3-4 minutes until light and fluffy. You'll see the mixture nearly double in volume and become pale in color. This aeration creates the bread's signature tender crumb.

Here's the thing - don't rush this step. The butter should be completely smooth with no graininess remaining. If you skip this proper creaming, you'll end up with a dense, cake-like texture instead of the light, moist bread we're after. I press down on the butter occasionally to check - when it springs back immediately, it's ready.

Add the 2 whole large eggs one at a time, mixing on low speed for 30 seconds after each addition until fully incorporated. Then add the 2 teaspoons vanilla extract and 0.5 cup milk, mixing just until combined. Scrape down the sides of the bowl to ensure everything is evenly incorporated.

Now fold in the grated zucchini using a silicone spatula. Be gentle - you're just combining, not overmixing. The zucchini will add moisture and subtle sweetness while keeping the bread tender. Add the dry ingredients mixture in two batches, mixing on low speed just until combined after each addition. Overmixing develops gluten and makes the bread tough.

Preheat your oven to 350°F and grease two 8x4-inch loaf pans thoroughly with butter or baking spray. Divide the batter evenly between the prepared pans. For each pan, sprinkle about 0.75 cup of the toasted walnuts evenly over the batter, then use a knife to swirl them gently through the batter in a circular motion.

Bake for 50-55 minutes until a toothpick inserted in the center comes out clean and the top is golden brown. I like to tent the pans loosely with aluminum foil after 30 minutes to prevent over-browning while still allowing the bread to cook through. The bread is done when it springs back slightly when pressed in the center.

Remove the bread from the oven and let it cool in the pans for 10 minutes before transferring to a wire rack to cool completely. This resting period allows the bread to set properly and prevents it from falling apart when slicing. The internal temperature should reach 100°F before slicing for the best texture.

Slice the bread while still warm for the most moist, tender results. Each slice should have a perfect balance of tender crumb, subtle zucchini sweetness, and those beautiful walnut swirls throughout. Store any leftovers wrapped tightly at room temperature for up to 3 days or freeze for up to 3 months for freshness.

Flavor customization for this recipe

Sweetness Adjustments

This recipe balances sweetness perfectly, but you can tweak it to your taste. For a less sweet version, reduce the brown sugar to ¾ cup and add 2 tbsp maple syrup—the molasses notes complement the zucchini beautifully.

If you prefer extra sweetness, increase the brown sugar to 1¼ cups and add 1 tbsp lemon zest to brighten the flavor. 🍯

Spice Variations

Swap out the cinnamon for other warm spices to change the profile. Try ½ tsp nutmeg and 1 tsp cardamom for a Middle Eastern twist, or add ½ tsp ginger and ¼ tsp cloves for a spiced chai-inspired bread.

For a citrus kick, fold in 1 tbsp orange zest with the vanilla extract—it pairs wonderfully with the walnuts.

Nutty Alternatives

Walnuts are classic, but other nuts work too. For a Southern-style bread, use pecans—their buttery flavor enhances the sweetness. Try hazelnuts or almonds for a lighter texture, or chopped dates for a chewy, caramelized twist. Toast all nuts for 5-7 minutes at 350°F to intensify their flavor before mixing.

Gluten-Free Adaptation

Replace the all-purpose flour with a 1:1 gluten-free baking flour blend (like Bob’s Red Mill or King Arthur). Add ½ tsp xanthan gum to improve texture, and increase the milk to ⅔ cup to compensate for dryness.

The bread will be slightly denser but still moist—pair it with a schmear of cream cheese for extra richness. 🌾

Dairy-Free Swaps

Use unsweetened almond milk or oat milk instead of cow’s milk, and substitute the butter with vegan butter (like Miyoko’s or Earth Balance). For extra moisture, add 2 tbsp applesauce to the batter.