Zucchini Brownies (My Mother-in-Law’s Old-Fashioned Family Recipe)

I first had these zucchini brownies as a teenager, long before I became part of the family. They were one of my mother-in-law’s recipes, and I loved them from the very first bite.

The shredded zucchini practically disappears into the brownies, so you cannot see or taste it—it simply makes them incredibly moist. Then there is that warm chocolate chip frosting: it melts in your mouth with a soft, almost fudge-like texture that makes these brownies truly special—the reason Scott jokingly calls them “special brownies.”

Why You’ll Love This Recipe

These are the kind of old-fashioned zucchini brownies you make once and then think about every time you have extra zucchini on the counter.

• The zucchini disappears: It melts right into the chocolate batter, adding plenty of moisture without a visible vegetable texture.
• That frosting is unforgettable: The cooked chocolate chip frosting has a soft, melt-in-your-mouth texture that is different from a regular brownie frosting.
• Kids love them: They taste like a rich chocolate dessert, not a zucchini recipe, so they are an easy win with kids.
• They use garden zucchini: This recipe turns two cups of shredded zucchini into a pan of brownies everyone will be happy to eat.
• They feed a crowd: A simple 9×13 pan makes enough to bring to a potluck, serve after supper, or share with family.

It is a simple family recipe, but that frosting makes it feel like something extra special.

Ingredients You’ll Need

You’ll need simple pantry ingredients, fresh zucchini, and chocolate chips for the frosting.

For the Zucchini Brownies

• 2 cups shredded zucchini
• 2 cups flour
• 1 egg
• 1¼ cups sugar
• 1 teaspoon salt
• ½ cup oil
• ½ cup cocoa
• 1½ teaspoons baking soda
• 2 teaspoons vanilla
• ½ cup nuts, optional

For the Chocolate Chip Frosting

• 1½ cups sugar
• 6 tablespoons canned milk
• 6 tablespoons margarine
• ¾ cup chocolate chips

Regular milk works in place of canned milk if needed.

How to Make Zucchini Brownies

These old-fashioned zucchini brownies are simple to make and topped with a warm chocolate chip frosting that melts in your mouth.

1. Prepare the Pan and Zucchini

Preheat the oven to 350°F and grease a 9×13-inch baking pan. Finely shred the zucchini, but do not squeeze out any moisture.

2. Combine the Dry Ingredients

In a large bowl, stir together the flour, sugar, cocoa, baking soda, and salt.

3. Mix the Wet Ingredients

In a separate bowl, stir together the shredded zucchini, oil, egg, and vanilla. Pour the wet ingredients into the bowl of dry ingredients and stir just until combined, then fold in the nuts if you are using them.

4. Bake the Brownies

Spread the batter evenly in the prepared pan. Bake for 30 minutes, until a toothpick inserted near the center comes out mostly clean.

5. Make the Chocolate Chip Frosting

Combine the sugar, canned milk, and margarine in a saucepan. Bring the mixture to a boil and boil for 1 minute, then remove it from the heat and stir in the chocolate chips until melted and smooth.

6. Frost the Brownies

Let the brownies cool until they are warm but not straight from the oven. Stir the frosting until it starts to thicken, then spread it evenly over the warm brownies.

Let the frosting set before cutting the brownies into squares.

Tips for the Best Zucchini Brownies

A few small details make all the difference in keeping these brownies soft and getting that frosting just right. They are simple, old-fashioned brownies, so there is no need to overthink them.

Shred the Zucchini Finely

Use the fine shredding blade on a food processor or the small side of a box grater. The zucchini will disappear right into the brownies as they bake, so do not squeeze out the moisture.

Do Not Overmix the Batter

Stir the wet and dry ingredients together just until combined. Overmixing can make the brownies more cake-like instead of keeping that dense brownie texture.

Let the Frosting Thicken

After stirring in the chocolate chips, keep stirring the frosting until it begins to thicken. It should still be warm and spreadable when you pour it over the brownies.

Use Canned Milk

The original recipe calls for canned milk, which is sweetened condensed milk. It gives the frosting its rich, soft texture.

Leave Out the Nuts

The nuts are completely optional. I leave them out when I make these for my family.

Storing Zucchini Brownies

Store leftover brownies in an airtight container at room temperature for up to 3 days. If you need to keep them longer, refrigerate them for up to 1 week. Just let them sit out for a few minutes before eating.

You can also freeze these brownies, with or without the frosting.

If you freeze them without the frosting, it is easier, because sometimes the frosting tends to get messed up when you stack the brownies in the freezer. You just simply make the frosting after the brownies thaw.

If you freeze them with the frosting, place the cut brownies in a freezer-safe container with parchment paper in-between the layers, to prevent them from sticking to each other.

You can freeze them for up to 3 months.

Frequently Asked Questions

Here are a few helpful answers for making these zucchini brownies, including how to handle the zucchini and what to use in the frosting. It is a simple recipe, but these little details will help them turn out just right.

Do You Peel the Zucchini for Brownies?

Nope! Just wash it well and shred it finely so it disappears into the brownies as they bake.

Do You Squeeze the Water Out of the Zucchini for Brownies?

No. The water is what keeps these brownies so moist.

Can I Make These Zucchini Brownies Without Nuts?

Yes, the nuts are completely optional. I leave them out when I make these for my family.

What Is Canned Milk?

Canned milk is sweetened condensed milk. It is thick, sweet, and helps give the chocolate frosting its soft, melt-in-your-mouth texture.

Can I Use Regular Milk Instead of Canned Milk?

Yes, my husband’s aunt often used regular milk. The frosting was a little different, but it still worked. I highly recommend the canned milk though.

Can I Use Butter Instead of Margarine?

Yes, I use butter. It gives the frosting a slightly richer flavor.

Why Are My Zucchini Brownies Dry?

They may have baked too long, or the zucchini may have been squeezed dry before adding it to the batter. Bake them for the listed time and keep the moisture in the shredded zucchini.

Slow Down and Savor It

Every family seems to have a few recipes that become part of their story, and these zucchini brownies are one of those for us.

I have always loved brownies, but when my mother-in-law made these when I was a teenager, they quickly became my favorite.

I do not bake with zucchini very often because we usually love to eat ours fried, but when I do, these are the brownies I make.

My own mom makes a Texas-sized zucchini double chocolate muffin that is good too, but it has nothing on these brownies!

Now, every time I make a pan, Scott gets to joke about his “special brownies.”

Give them a try when you have zucchini sitting on the counter! Share them with your family. Maybe they’ll become part of your story, too.

Slow down and savor it.

More Zucchini Recipes

If you still have zucchini to use up, there are plenty of ways to enjoy it besides brownies. From sweet breads to simple suppers, these recipes will help you make the most of your garden harvest.

Lemon Zucchini Bread: A bright, sweet quick bread that is perfect for using up shredded zucchini.

Stuffed Zucchini: A hearty, simple meal when you have larger zucchini ready to pick.

Fried Zucchini: Our favorite way to eat fresh garden zucchini.

How to Freeze Zucchini: An easy way to save extra zucchini for later.

What to Harvest in August: A Northern Minnesota Guide: Find more zucchini recipe ideas, along with what else is ready to harvest from the garden.

Whether you use it fresh or freeze it for later, zucchini is one of those garden vegetables that gives you plenty to work with.