These ultra fudgy frosted zucchini brownies are the answer to that pile of zucchini taking over your counter at the end of summer. They are rich, deeply chocolatey, and dense in the way a really good brownie should be, with a thick layer of chocolate frosting on top. And hiding inside every pan is two full cups of shredded zucchini, which nobody is going to guess is in there!
We know that for a fact, actually. One of our taste testers had a small existential moment when he tried the final version of these and found out afterward that they were loaded with vegetables. He had no idea. That is the whole point of a good zucchini dessert, and it is the same trick we use in our chocolate chocolate chip zucchini muffins.
Getting here took some work. In the first rounds of testing we used baking powder and baking soda, mostly because so many other zucchini brownie recipes do. The result was good, but cakey, and cakey is not what we were going for. We wanted these to taste like our easy homemade brownies, which meant pulling the leaveners out entirely. The final version has the texture we were chasing: fudgy without being underbaked, rich, and dense.
As for the frosting, our thinking was pretty simple. If you are going to sneak this many vegetables into a dessert, you may as well go all the way and cover them in chocolate.
And if you still need more recipes using zucchini, we’ve put all of ours into one resource guide for easy browsing for you!
You’ll Love These Frosted Zucchini Brownies
Genuinely fudgy, not cakey. No baking powder or baking soda here, which is exactly what gives these the dense, rich texture you want from a brownie.
Two full cups of hidden zucchini. The zucchini disappears right into the chocolate as it bakes. You get moisture and a great texture, and no one notices it’s in there.
A great way to use up a zucchini glut. If your garden (or your neighbor’s garden) is producing faster than you can keep up with, or you got a little too excited at the farmers market like I often do, this is a fun place to put some of it.
That frosting. A thick, fudgy chocolate frosting takes these from good to hard to walk away from.
Ingredients for Chocolate Zucchini Brownies
- Salted butter. Melted and cooled for the brownies, and at room temperature for the frosting. Salted butter adds just enough depth to balance all that chocolate.
- Granulated and brown sugar. Using both is what gives these their flavor and chew. The brown sugar brings a little molasses depth along with it.
- Neutral oil. A small amount alongside the butter helps keep the brownies moist and fudgy as they cool.
- Eggs. Provide structure and richness, and help hold everything together without the use of leavening agents.
- Vanilla extract. Rounds out and deepens the chocolate flavor.
- All-purpose flour. Just enough to give the brownies structure. Any more and you drift into cake territory.
- Cocoa powder. Does the heavy lifting on chocolate flavor in both the brownies and the frosting.
- Grated zucchini. The star of the show, even though nobody will know it. Do not drain it, since that moisture is part of what makes these fudgy.
- Chocolate chips. Adds pops of melty pockets of chocolate throughout, a must in my book! You can also use chocolate chunks if desired.
- Powdered sugar. Sweetens the frosting and gives it body without any graininess.
- Heavy cream. Adds moisture and loosens the frosting into something thick but spreadable. Milk works here too if that is what you have!
Every measurement and the complete directions are waiting for you in the recipe card at the bottom of this post.
Helpful Equipment
Use a metal 9×9 square pan. Metal conducts heat more evenly than glass or ceramic, which means the middle of the pan actually finishes around the same time as the edges instead of lagging behind while the corners overbake. A simple box grater handles the zucchini, and a hand mixer makes quick work of the frosting.
How to Make Zucchini Brownies
Prep your pan. Preheat the oven to 350°F and grease a 9×9 metal baking pan. Lining the greased pan with parchment paper makes lifting the whole slab out much easier later if you’d prefer to not serve these from the pan.
Combine the butter, sugars, and oil. In a large mixing bowl, stir together the melted and cooled butter, both sugars, and the oil.
Whisk in the remaining wet ingredients. Add the eggs, vanilla extract, and salt, whisking until everything is smooth and combined.
Add the dry ingredients. Slowly mix in the flour and cocoa powder, stirring only until about 75% combined. You should still see streaks of flour at this stage, and that is what you want.
Fold in the zucchini and chocolate chips. Gently fold both in until the batter is just combined. Do not overmix here. The batter will be very thick, which is normal.
Spread batter into the pan and bake. Transfer the batter to the prepared pan and use a spatula to push it into the corners in an even layer. Bake for 28 to 32 minutes, or until a toothpick inserted in the center comes out with only a few moist crumbs. The center should be just set to the touch and should not jiggle or look wet.
Cool completely. Let the brownies cool in the pan for at least 30 minutes, and 1 to 2 hours if you have the time. They need to be fully cool before you frost them.
Make the frosting. Using a hand mixer, beat the room temperature butter on medium speed until creamy. Add the powdered sugar, cocoa powder, and heavy cream, starting on low speed.
Increase to high speed once the dry ingredients start to work in. Beat until all ingredients are incorporated and smooth, adding another splash of cream as needed.
Frost. Spread the frosting over the cooled brownies in an even layer.
Serve and enjoy! Slice the frosted brownies into 16 squares, serve, and enjoy!
Do You Squeeze the Water Out of the Zucchini?
No, and this is where a lot of zucchini brownie recipes disagree with each other. Some will tell you to wring the shredded zucchini out in a kitchen towel before it goes in the bowl. Do not do that here. The moisture in the zucchini is part of what makes these brownies fudgy, and it is also what brings the batter together. Grate it, add it, and leave the liquid alone.
You also do not need to peel the zucchini. The skin is thin and softens completely during baking, and it disappears into all that cocoa.
Easy Zucchini Brownie Variations
- Skip the frosting. These are still great as a plain brownie if you would rather keep things simple. I like the frosting on there, because if you are going to sneak veggies into a dessert, they may as well get a little frosting.
- Dust with powdered sugar instead. If you want something lighter than frosting but not totally bare, a dusting of powdered sugar over the cooled brownies is a nice middle ground.
- Add nuts. Fold in chopped walnuts or pecans along with the chocolate chips for some crunch.
- Change up the chips. Dark chocolate, milk chocolate, chocolate chunks, or a mix all work. White chocolate chips are a nice contrast against how dark these are.
Expert Tips for Fudgy Brownies with Zucchini
Reach for metal over glass. A metal pan heats evenly, so you avoid the classic problem of overdone edges wrapped around a middle that is still raw.
Pull them out a little early. For the best texture, err on the side of caution and pull them out earlier (vs. over baking them). An underbaked brownie can be saved, a dry one cannot. When the toothpick comes out with a few moist crumbs clinging to it, they are done. The brownies will keep setting up as they rest in the pan.
Give them time to cool. Waiting is the hardest part, but the texture improves and they slice much more cleanly once they have set for at least 30 minutes (1-2 hours is better if you have the time).
Do not overmix once the flour goes in. Stopping at about 75 percent combined and then folding in the zucchini and chips keeps these tender instead of tough.
How to Store Zucchini Brownies with Frosting
Once frosted, store these in an airtight container at room temperature for up to 3 days, or in the refrigerator for up to 5 days. If you are stacking them, put a sheet of parchment or wax paper between the layers so the frosting does not stick to the brownies above it.
These freeze well too. For the best results, freeze them unfrosted. Cool the brownies completely, wrap the slab or the individual squares tightly, and store in a labeled freezer-safe container for up to 3 months. Thaw at room temperature, then frost before serving.
Zucchini Brownies Recipe FAQs
Not at all. The zucchini disappears into the batter as it bakes and gets completely covered by the cocoa and chocolate chips. What it leaves behind is moisture and a fudgy texture. Our taste testers had no idea until we told them.
The most common culprit is leavening. A lot of zucchini brownie recipes call for baking powder or baking soda, and that is exactly what pushes them toward cake. We tested it that way early on and pulled it for that reason. Overmixing the batter after the flour goes in can do it too.
No. The skin is thin, it softens completely as the brownies bake, and it disappears into the chocolate. Just wash it, grate it, and add it in.
You can, with one caveat. Two cups of thawed zucchini is not the same volume as two cups of fresh, so freeze it in measured 2 cup portions while it is still fresh if you plan ahead. Thawed zucchini also releases a lot of liquid, and just like with fresh, you want to add all of that to the batter rather than draining it off.
Love This Recipe? Try One of These Recipes Using Zucchini Next!
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Fudgy Chocolate Zucchini Brownies
Equipment
Ingredients
For the Brownies
- ½ Cup salted butter, melted and cooled
- ¾ Cup brown sugar (light or dark)
- ¾ Cup granulated sugar
- 2 Tablespoons neutral oil (canola or vegetable)
- 2 large eggs
- 2 teaspoons vanilla extract
- ½ teaspoon salt
- 1 + ¼ Cup all-purpose flour
- ½ Cup unsweetened cocoa powder
- 2 Cups grated zucchini (do NOT drain!)
- 1 Cup semi-sweet chocolate chips
For the Frosting
- ½ Cup salted butter, softened to room temperature
- 1 + ½ Cup powdered sugar
- ⅓ Cup cocoa powder
- 3 Tablespoons heavy cream (or milk)
Instructions
For the Brownies
- Prep the pan. Preheat the oven to 350°F. Grease a 9×9 metal baking pan and set aside. If desired, line the greased pan with parchment paper for easy removal.
- Combine the butter, sugars, and oil. In a large mixing bowl, stir together the melted and cooled butter, granulated sugar, brown sugar, and oil.½ Cup salted butter, melted and cooled¾ Cup brown sugar¾ Cup granulated sugar2 Tablespoons neutral oil
- Whisk in the eggs, vanilla, and salt. Whisk until smooth and fully combined.2 large eggs2 teaspoons vanilla extract½ teaspoon salt
- Add the flour and cocoa powder. Slowly mix in until about 75% combined. You will still see streaks of flour at this point, and that is what you want.1 + ¼ Cup all-purpose flour½ Cup unsweetened cocoa powder
- Fold in the chocolate chips and zucchini. Gently fold until the batter is JUST combined, being careful not to overmix. The batter will be very thick, which is normal.2 Cups grated zucchini1 Cup semi-sweet chocolate chips
- Spread into the pan. Transfer the batter to the prepared pan and use a spatula to spread it into the corners in an even layer.
- Bake for 28 to 32 minutes. The brownies are done when a toothpick inserted in the center comes out with only a few moist crumbs. The center should be just set to the touch and should no longer jiggle or look wet.
- Cool completely before frosting. Let the brownies cool in the pan for at least 30 minutes (1 to 2 hours if you have time) before frosting. If desired, you can remove them from the pan after the initial cool time.
For the Frosting
- Beat the butter. Using a hand mixer, beat the room temperature butter on medium speed until creamy.½ Cup salted butter, softened to room temperature
- Add the remaining ingredients. Add the powdered sugar, cocoa powder, and heavy cream. Start on low speed and increase to high once the dry ingredients begin to work in. If it looks crumbly, or isn't incorporating well, add another small splash of cream (or milk).1 + ½ Cup powdered sugar⅓ Cup cocoa powder3 Tablespoons heavy cream (or milk)
- Frost and serve. Spread the frosting over the cooled brownies in an even layer, then slice and serve.
Notes
- Skip the frosting. If preferred, these are still great as a plain brownie if you would rather keep things simple.
- Dust with powdered sugar instead. If you want something lighter than frosting but not totally bare, a dusting of powdered sugar over the cooled brownies is a nice middle ground.
- Add nuts. Fold in chopped walnuts or pecans along with the chocolate chips for some crunch.
- Change up the chips. Dark chocolate, milk chocolate, white chocolate, chocolate chunks, or a mix all work.
Meredith says
My new favorite way to use zucchini, OMG YUM!!! So fudgy and decadent, you’d never know there are veggies in there!