These zucchini brownies with marshmallow frosting are a rich, delicious way to use up those zucchini that are becoming bountiful in gardens around the Midwest. Your average brownie ingredients are in this recipe- flour, sugar, vanilla, soda, etc. The brownies do not have any dairy or egg in them, but you will want to wash this rich treat down with an ice cold glass of white milk! The creamy marshmallow frosting does include dairy–but could be substituted..
Looking for more dairy/egg free desserts? Be sure to check out our wacky cake recipe.
Updated this recipe in July 2025 to add nutrition information, FAQs and how to shred zucchini info.
Why you will love these brownies
- have hidden veggies in them, but no lack of flavor and chocolate!
- frosting is very simple to make
- brownies have no “special” ingredients with the exception of zucchini
Simple Ingredients in Zucchini Brownies
Flour- pretty self explanatory. Along with white granulated sugar, baking soda, cocoa and salt.
Zucchini- I used both shredded & diced zucchini. The shredded ‘blends’ better in the recipe but the small diced works good too. It just might be a bit more noticeable.
Vegetable oil- you could also use canola oil if in a pinch. Vanilla,
Marshmallow Frosting: the ingredients for this are also probably things you have in your fridge & pantry. Butter, milk, chocolate chips, vanilla and mini marshmallows. I usually don’t have mini marshmallows around, so just cut up large ones.
I cannot take credit for this recipe. It is another recipe I have used from Rocking Bar H. Check out their banana bar recipe- it is to amazing, too!
How to Make Zucchini Brownies:
- Combine Dry Ingredients
In medium size bowl, combine your dry ingredients. Set aside for now.
- Combine Wet Ingredients
If you haven’t yet- prep your zucchini. Then, in a separate bowl combine zucchini, sugar, oil, vanilla.
- Combine
Combine the dry and wet ingredients. You can mix by hand or with a mixer.
- Bake
Pour the batter into a greased 9×13 pan. Bake at 350 F for 30 minutes or until toothpick comes out of middle pretty clean. (Doesn’t have to be completely clean if you like them fudgy)
- Frosting
While brownies are cooling, make the frosting.
In a small sauce pan, melt the butter- then add sugar and milk. Bring to a boil and continue on a low boil for 1 minute. Remove from heat. Add the chocolate and marshmallows. Pour over cooled brownies.
FAQs
Store on counter in airtight container for up to 1 week.
You can also freeze these baked brownies in freezer safe container for up to 3 months. Just set on counter to thaw.
Absolutely! Wash, peel, dice/shred and portion into 2 cup freezer bags to have on hand for baking.
Looking for a quick, easy way to dice zucchini and other veggies? This one on amazon is my favorite-veggie chopper.
It lasts at least 3 months in freezer, but if storing properly and in a deep freeze many times up to 1 year is still good quality.
If you love freezer meals and prep- be sure to check out our roundup of favorite freezer meals!
Yes. I have cut up larger marshmallows and substituted for the mini when in a pinch.
Yes, feel free to use whatever frosting recipe you like– just make sure it is appropriate for brownies.
It acts as a texture or moisture booster–which is great for brownies!! It can usually replace part of fat or liquid in a recipe too (less oil or butter!). It helps the brownies taste extra fudgy.
Wash the zucchini and cut ends off. Then, use a large cheese grader to shred zucchini. You could also dice up very small but I like shreds better- it is more picky eater friendly that way too.
More Zucchini and Dessert Recipes
If you have an abundance of zucchini, try our zucchini noodle pasta recipe.
Zucchini Chocolate Chip Mini Muffins
Chocolate Chip Cookie Bars are another rich popular recipe our kids enjoy
Protein Banana Bread is a healthier baked good to try for your family
Our Fudgy Bars with Sweetened Condensed Milk are another rich treat
Maple Apple Bars are another late summer/fall dessert recipe that can be a hit!
Need a moist chocolatey. dessert without the temptation of eating the whole pan? Try our chocolate mug cake recipe.
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The Easiest Zucchini Brownies (with Marshmallow Frosting!)
Equipment
- 1 9×13 pan
- measuring utensils
Ingredients
- 2 cups flour
- 1/3 cup cocoa
- 1-1/2 tsp baking soda
- 1 tsp salt
- 2 cups zucchini shredded or diced very small
- 3/4 cup vegetable oil or canola
- 2 tsp vanilla
- 1-1/2 cups white sugar
Marshmallow Frosting
- 1/4 cup butter
- 1 cup sugar
- 1/4 cup milk
- 1/2 cup chocolate chips
- 1/2 cup miniature marshmallows or cut up large marshmallows if in a pinch
- 1 tsp vanilla
Instructions
- In a medium sized bowl, combine flour, cocoa, baking soda & salt
- Prep Zucchini: wash and shred with cheese shredder or veggie tool.
- In a separate bowl, combine the prepped zucchini, sugar & oil. Add the wet ingredients to the dry ingredient bowl. Stirring by hand until well combined. Then add in the vanilla.
- Pour batter into a greased 9×13 pan. Bake at 350 degrees for about 30 minutes. Until tooth pick comes out pretty clean in middle.
Frosting
- Melt the butter in a pan on medium heat. Then add sugar & milk. Bring to boil over medium-high heat, stirring often. Reduce heat & cook for an additional minute after brought to boil.
- Remove from heat. Stir in the chocolate chips & marshmallows until completely melted. Then stir in vanilla. Let sit for a couple minutes, stirring a bi, until frosting is a bit thicker. Pour the frosting over the brownies & spread on cooled brownies.
Notes
Nutrition
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Fudgey and a great way to use up zucchini from garden!
We’ve made these several times the past two summers. Our go-to with a surplus of zucchini. I peel the zucchini so the kids do see the dark green peel.
I’m glad you like the recipe- that is a great idea to peel the zucchini! Thanks for the comment, Amanda!