Streusel Topped Chocolate Zucchini Muffins

Extra moist with a crackly top and packed full of zucchini, these streusel-topped Chocolate Zucchini Muffins are the most delicious way to eat your veggies! 

6 well muffin tin filled with 5 zucchini muffins and one well filled with chocolate chips

It’s the end of summer.  Your zucchini is piling up.  It just keeps coming in your CSA box or growing to epic sizes in your garden.  You’re sick of eating for dinner.  What on earth are you supposed to do with all that excess zucchini?

Streusel-topped chocolate zucchini muffins, that’s what.  Pretty much the best way to eat your veggies, amirite?  (Well, maybe not THE best – I mean, this double chocolate zucchini bread, frosted zucchini brownies, and zucchini bundt cake are all pretty great, too!)

But this year, we’re doing a Muffin of the Month series, and it’s July, and we have a lot of zucchini. So! Extra chocolatey, packed-full-of-zucchini, muffins to the rescue!

If you’re NOT tired of zucchini for dinner, allow me to suggest the following delicious options: this beautiful spiral vegetable tart, the most popular recipe on Bunsen Burner Bakery.  Or maybe a tomato and zucchini galette? How about this easy, spicy, one skillet Mexican zucchini?

No? Not into more zucchini for dinner?  Then read on for extra moist, extra chocolatey muffins… with a big heaping pile of zucchini.

stack of chocolate zucchini muffins with one muffin cut open to show the dark chocolatey interior

Ingredients and Substitutions

  • Sugar: We’re going to use both granulated and brown sugar for these muffins. The brown sugar provides extra moisture and a slightly deeper taste, but it can be substituted for granulated sugar.
  • Vegetable Oil: Use any neutral cooking oil, like vegetable oil, canola oil, or grapeseed oil. You can even substitute the oil with applesauce to lower the fat content of the muffins; the muffins just won’t be as rich and fudgy.
  • Eggs: Two large eggs, at room temperature.
  • Yogurt: Use plain full-fat yogurt for the best texture and flavor, or substitute sour cream instead.
  • Flour: This recipe is written for all-purpose flour. To keep these muffins gluten-free, use a 1-for-1 gluten-free baking mix. You can also swap half the all-purpose flour with whole wheat flour for extra fiber; the muffins will just be more dense.
  • Cocoa Powder: Use Dutch-processed cocoa powder for these muffins.
  • Chocolate Chips: We’ll use regular-size chocolate chips in the muffins and miniature chocolate chips in the streusel. You can substitute white chocolate chips, peanut butter chips, or dried fruit or nuts for a different flavor.
  • Grated Zucchini: The most important part! Grate your zucchini well and squeeze out any extra moisture before making these muffins; too much extra moisture results in a slightly rubbery texture.
step by step photos showing how to make double chocolate zucchini muffins

Double Chocolate Zucchini Muffins

These muffins are so chocolatey, it’s easy to forget that they’re actually stuffed full of zucchini!

We’ll use Dutch-processed cocoa powder for a rich, deep chocolate flavor, and then pile in some chocolate chips (because chocolate chips make everything better… right?!)

And of course, we’re including zucchini. Lots of zucchini! Grated and then squeezed to remove any excess water. You can even grate this zucchini a day or two in advance and leave it uncovered in the refrigerator – the cold air will start to dry out the zucchini even more.

Have you ever wondered why adding zucchini to baked goods like muffins creates such moist, tender treats? We can figure out why with my favorite subject… kitchen chemistry!

Kitchen Chemistry

Zucchini is almost entirely made up of water — it has a 95% water content. As the muffins bake, this moisture is released into the batter, keeping it from drying out, resulting in incredibly moist muffins. The water in the zucchini diffuses into the batter through the process of osmosis, moving from an area of high concentration to an area of low concentration. The end result is a perfectly moist muffin and zucchini that melts right into the muffin with no distinguishable squishy zucchini pieces.

Chocolate Chip Streusel Topping

Technically, this streusel topping is optional. You can enjoy double chocolate zucchini muffins with nothing at all on top. But if you ask my kids, the streusel is non-negotiable and the best part!

Streusel is often made by cutting cold butter into flour, but this version is even easier. All we’re going to do is mix together some brown sugar, granulated sugar, cinnamon, and miniature chocolate chips. As the chocolate chips heat in the oven and start to melt, they’ll form a perfectly crunchy, sugary streusel topping for the muffins.

side view of domed muffins topped with streusel towering over the side of a muffin tin

Super Tall Muffin Domes

We’re also going to use my favorite muffin tricks to get tall domed tops and beautiful big muffins. First, fill the muffins up to the top of the muffin pan. These use a standard-size muffin tin, and the batter fills them almost the whole way to the top.

Second, we’ll bake them at a high temperature (425 °F) for 5 minutes before lowering the temperature. This initial heat sets of a big burst of steam, which pushes up from the center of the muffin and sets the structure for the big domed top. Then we’ll turn down the oven so the muffin tops don’t burn and the middle of the muffin can cook through.

chocolate zucchini muffin with a sugar crumb topping on an unwrapped parchment paper muffin liner
  • Muffin Tins: These are baked in standard-size muffin tins and will make 12 large muffins.
  • Mixing Bowls: My favorite set of glass mixing bowls!
  • Box Grater: Zucchini is so easy to grate, I find it’s just as quick to grate it by hand with this type of grater as it is to pull out a food processor.
  • Dutch Processed Cocoa Powder: Good quality, higher-fat cocoa powder produces superior chocolate muffins.
  • Cooling Racks: These racks are sturdy but fold down flat for easy storage.
stack of multiple domed chocolate zucchini muffins piled on top of each other

Tips and Tricks for the Best Chocolate Zucchini Muffins

  1. When combining the wet and dry ingredients, mix until just incorporated. Overmixing can lead to dense muffins. Some lumps are okay in the batter!
  2. Make sure to grate the zucchini and then squeeze out the excess moisture to prevent the muffins from getting soggy.
  3. For easy release from the pan, grease the pan well or use parchment paper muffin liners.
  4. After five minutes, remove the muffins from the tin and allow them to cool on a wire rack. This allows the steam from the bottom of the muffin tin to escape and prevents the bottoms of the muffins from becoming too moist.
  5. Customize your muffins by adding chopped nuts, dried fruit, or even a sprinkle of flaxseeds for added texture and nutrition.
  6. Store any leftover muffins in an airtight container at room temperature for up to 3 days, refrigerate for up to a week, or freeze the zucchini muffins for up to 3 months.

More Chocolate Chip-Packed Recipes:

2023 Muffin of the Month Recipe

chocolate zucchini muffin cut open to show the dark chocolaty interior

Streusel Topped Chocolate Zucchini Muffins

Yield: 12 muffins
Prep Time: 10 minutes
Cook Time: 20 minutes
Total Time: 30 minutes

Extra moist with a crackly top and packed full of zucchini, these streusel-topped chocolate zucchini muffins are the most delicious way to eat your veggies!


For the Muffins:

  • 1/2 cup (99 grams) granulated sugar
  • 1/4 cup (53 grams) brown sugar
  • 1/2 cup (99 grams) vegetable oil
  • 2 large eggs, room temperature
  • 1/4 cup (57 grams) plain yogurt
  • 2 teaspoons vanilla extract
  • 1 1/2 cups (180 grams) all purpose flour
  • 1/2 cup (42 grams) Dutch process cocoa powder
  • 1 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 1/2 teaspoon salt
  • 1/2 cup (85 grams) chocolate chips
  • 2 packed cups (300 grams) grated zucchini, dried well

For the Streusel:

  • 2 tablespoons granulated sugar
  • 2 tablespoons brown sugar
  • 1/2 teaspoon cinnamon
  • 1/2 cup (88 grams) miniature chocolate chips


  1. Preheat the oven to 425 °F. Grease a 12-well muffin tin or line with muffin liners.
  2. Using a whisk, stir together the granulated sugar, brown sugar, oil, and eggs until well combined. Add the yogurt and vanilla, whisking until combined.
  3. Add the flour, cocoa powder, baking powder, baking soda, and salt, to the wet ingredients and stir with a rubber spatula until just combined. Fold in the chocolate chips and zucchini.
  4. In a small bowl, mix together the granulated sugar, brown sugar, cinnamon, and miniature chocolate chips to make the streusel topping.
  5. Divide the batter equally among the 12 wells of the muffin tin. Sprinkle the topping over the cupcakes.
  6. Bake at 425 ° for 5 minutes. Keep the muffins in the oven and reduce the temperature to 350 °F. Bake for an additional 14-16 minutes, or until a tester inserted into the center of the muffins comes out clean. Cool for 5 minutes in the pan, then remove to a wire rack to cool completely.


  1. Don't overmix the batter - a few lumps are okay. Overmixing can lead to dense muffins.
  2. Squeeze excess moisture out of the zucchini to prevent the muffins from getting soggy.
  3. Customize your muffins by adding chopped nuts, dried fruit, or even a sprinkle of flaxseeds for added texture and nutrition.
  4. Store any leftover muffins in an airtight container at room temperature for up to 3 days, refrigerate for up to a week, or freeze the zucchini muffins for up to 3 months.

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Streusel Topped Chocolate Zucchini Muffins: extra moist with a crackly topping and packed full of zucchini, these muffins are the most delicious way to eat your veggies! Freezer friendly and perfect to share!

This recipe was first posted in August 2017 and updated with new photos and helpful tips in July 2023.