Fabulous double chocolate zucchini muffins with walnuts added to the mix. Wonderfully moist and chocolatey and a great use for that extra zucchini harvest.

chocolate zucchini muffins on cooling rack

These chocolate zucchini muffins have the most wonderful texture, which is sturdy, but still moist. The double chocolate from both cocoa powder and chocolate chips makes these muffins rich in chocolate and with the added walnuts, they are almost brownie-like. And there’s lots of zucchini hiding in there, too!

Ingredients and Substitutions

Zucchini – for the base recipe, you will need one medium supermarket-sized zucchini. No need to peel.

Chocolate Chips – regular semi-sweet chocolate chips are all that’s needed for these muffins.

Cocoa Powder – natural unsweetened cocoa powder (not Dutch processed), is specified. Hershey’s Natural (not Special Dark) is a great option. Fry’s, which is common in Canadian kitchens is Dutch Processed.

Why not Dutch Processed? Well, it’s a chemical thing, but suffice it to say that using Dutch-processed instead of natural will interfere with the leavening process in this recipe and unexpected things may happen.

Espresso Powder – the bit of coffee powder added to the batter really heightens the chocolate flavour. If you don’t have espresso powder, instant coffee powder is fine, or simply omit it if you have neither on hand.

Vegetable Oil – I’ve always found that vegetable oil performs best in baking, so I do recommend it if you have it on hand. If not, use a similar neutral-tasting cooking oil, such as canola or sunflower.

Sour Cream – full-fat sour cream is recommended. If you don’t have sour cream, plain Greek yogurt is fine.

Walnuts – walnuts are the perfect addition to chocolate, for both flavour and a bit of crunch. If you want a nut-free muffin, simply omit it.

Step-by-Step Photos

  1. Measure out the shredded zucchini and place onto a tripled-up paper towel to drain a bit of moisture off of it. Grease a muffin tin (or line it with paper liners, if you like).
  2. Whisk together the dry ingredients in a large bowl.
  3. Add the chocolate chips and walnuts to the dry ingredients and stir in.
  4. Add the wet ingredients to the dry ingredients and stir just until combined.
  5. Add the shredded zucchini to the batter and fold in.
  6. Scoop batter into muffin cups (8 cups for the base recipe) and top with additional walnuts before baking.
chocolate zucchini muffins on cooling rack

Recipe Tips

  • Don’t squeeze or press any more moisture out of the zucchini, beyond letting it stand on the paper towel. The extra bit of moisture helps keep these muffins lovely and moist.
  • It can be a bit tricky to test these muffins for done-ness, as it is easy to hit a chocolate chip when testing, which may make it seem like they are not done. I like to test a couple of different spots in the muffin, just to be sure.

Storing and Freezing

Store baked muffins in an airtight container for several days or freeze up to 3 months for longer storage.

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chocolate zucchini muffins on cooling rack

Get the Recipe: Chocolate Zucchini Muffins

Fabulous double chocolate zucchini muffins with some walnuts added to the mix. Wonderfully moist and chocolatey.
4.88 stars from 8 ratings
Prep Time: 15 minutes
Cook Time: 20 minutes
Total Time: 35 minutes
Yield: 8 muffins


  • 1 1/2 cups zucchini, shredded
  • 1 cup all purpose flour, spooned and levelled
  • 1/2 cup natural unsweetened cocoa powder, not Dutch processed
  • 3/4 teaspoon baking soda
  • 1/4 teaspoon baking powder
  • 1/4 teaspoon salt
  • 1/4 teaspoon espresso powder, or instant coffee powder
  • 3/4 cup semi-sweet chocolate chips
  • 1/4 cup walnuts, chopped, plus more for topping
  • 2 large eggs
  • 1/4 cup vegetable oil, or canola oil
  • 1/4 cup full-fat sour cream, or Greek yogurt
  • 1/2 cup white granulated sugar
  • 1 teaspoon vanilla extract


  • Preheat oven to 425F (regular bake setting/not fan-assisted). Grease 8 muffin cups by spraying with baking spray (or line with paper liners, if you like.
  • Shred the zucchini and measure out. Place onto a tripled-up piece of paper towl and let stand while you mix the batter.
  • In a large bowl, whisk together the flour, cocoa powder, baking soda, baking powder, salt and espresso powder. Stir in the chocolate chips and walnuts.
  • In a medium bowl or 2-cup measuring cup, use a fork to mix together the eggs, oil, sour cream, white sugar and vanilla.
  • Add the egg mixture to the dry mixture and stir together just until combined. Add the shredded zucchini and fold in until combined.
  • Using a large scoop, scoop the batter into the muffin cups (8 muffin cups for the base recipe). Sprinkle the tops of the muffins with additional walnuts.
  • Bake muffins at 425F for 5 minutes, then reduce the oven temperature to 350F and bake for an additional 15-17 minutes, or until the muffins test clean when tested in the centre of the muffin. *Test in a couple of spots, as it is easy to hit a chocolate chip when testing, which may make it seem like the muffins aren't ready, even when they are.
  • Remove the muffins from the oven and allow to cool in the pan for 10 minutes, before removing to a cooling rack to cool completely.


Store muffins in an airtight container for 2-3 days. These muffins will also freeze well for up to 3 months.
Be sure to read the notes above this Recipe Card, for more tips on making this recipe, along with step-by-step photos that you might find helpful.
Cuisine: American, Canadian
Course: Snack
Serving: 1muffin, Calories: 337kcal, Carbohydrates: 38g, Protein: 6g, Fat: 19g, Saturated Fat: 7g, Polyunsaturated Fat: 6g, Monounsaturated Fat: 5g, Trans Fat: 0.1g, Cholesterol: 52mg, Sodium: 201mg, Potassium: 312mg, Fiber: 4g, Sugar: 20g, Vitamin A: 168IU, Vitamin C: 4mg, Calcium: 47mg, Iron: 3mg
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