These zucchini blondies with penuche fudge frosting are soft, chewy brown-sugar dessert bars made with finely shredded zucchini, vanilla, and a simple buttery batter. Bake them in a 13-by-9-inch pan for 25 to 30 minutes, cool completely, then cover them with a creamy cooked brown-sugar frosting for about 24 irresistible bars.
The blondies have a tender, moist crumb and a mellow caramel flavor, while the penuche frosting tastes like brown sugar fudge spread over the top. This is a wonderful Candy-category recipe for using a small zucchini in a dessert that feels familiar, generous, and special enough for a gathering.
Jump to RecipeWhy You’ll Love This Recipe
Zucchini blondies are an easy way to turn a humble summer vegetable into a rich, bakery-style dessert. The zucchini adds moisture without making the bars taste strongly vegetal, so the dominant flavors remain buttery vanilla and warm brown sugar.
The penuche frosting is the feature that makes these bars memorable. Butter, brown sugar, and milk are briefly boiled together, cooled, and beaten with confectioners’ sugar to create a smooth frosting with the flavor of soft brown-sugar fudge.
- Yield: About 24 bars from one 13-by-9-inch pan.
- Texture: Soft, tender, and lightly chewy with a creamy frosting layer.
- Timing: About 20 minutes of preparation, 25 to 30 minutes of baking, and roughly 30 minutes for cooling and frosting.
If you are serving these as part of a seasonal menu, a savory vegetable side such as this cheesy zucchini gratin can make good use of the rest of your squash.
Ingredients You’ll Need
The blondie batter begins with softened butter and packed light brown sugar. Beat those ingredients until blended so the sugar is distributed throughout the butter before adding the egg and vanilla.
Use all-purpose flour, baking powder, and salt for the dry mixture. The baking powder gives the bars enough lift to stay tender while still maintaining the dense, chewy character expected from a blondie.
For the zucchini, measure 1 cup after finely shredding it. Peeling is not needed, and the fine shreds disappear into the batter while contributing useful moisture.
The frosting needs a second 1/2 cup of butter, another cup of packed light brown sugar, 1/4 cup of milk, 2 cups of confectioners’ sugar, and 1 teaspoon of vanilla. Sift the confectioners’ sugar if it looks lumpy, since that helps the finished frosting become smooth more quickly.
- Bring the egg to room temperature when possible for easier mixing.
- Pack the brown sugar firmly into the measuring cup for the intended sweetness and frosting consistency.
- Lightly blot exceptionally watery zucchini, but do not squeeze it completely dry.
For another recipe idea when planning a comfort-food spread, you can pair the dessert with savory favorites such as this beef chorizo stuffing before bringing out the blondies.
How to Make It Step-by-Step
Step 1: Heat the oven to 350°F (175°C) and grease a 13-by-9-inch baking pan. Greasing the pan helps the blondies release cleanly after cooling and makes spreading the thick batter easier.
Step 2: Beat the softened butter and packed light brown sugar until blended. Add the room-temperature egg and vanilla, then beat until the mixture is evenly combined and creamy.
Step 3: In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually add this dry mixture to the butter mixture, mixing just until no obvious streaks of flour remain.
Step 4: Stir in the finely shredded zucchini just until it is evenly distributed. Avoid excessive mixing at this stage, because overworking the flour can make the bars less tender.
Step 5: Spread the batter in the prepared pan and smooth it into the corners. Bake for 25 to 30 minutes, checking that the center is set and that a toothpick comes out clean or with only a few moist crumbs.
Step 6: Leave the blondies in the pan and cool them completely. The bars need to be fully cool before frosting so the penuche layer stays thick instead of melting or sliding.
Step 7: Begin the frosting by melting the butter in a saucepan over medium heat. Stir in the brown sugar and milk, bring the mixture to a boil, and cook for 1 minute while stirring.
Step 8: Remove the saucepan from the heat and let the brown-sugar mixture cool to room temperature. This cooling period is important because confectioners’ sugar added to a hot syrup can produce a thin or uneven frosting.
Step 9: Gradually beat in the confectioners’ sugar and vanilla until the frosting is smooth. Spread it over the cooled blondies, then cut the slab into about 24 bars once the frosting has settled.
Pro Tips for Soft, Fudgy Blondies
Finely shred the zucchini so it blends naturally into every bite. A coarse shred can leave visible strands and make the batter harder to spread, while a fine shred distributes moisture throughout the pan.
Do not remove all the liquid from the zucchini. If the squash is dripping wet, lightly blot it with a paper towel or drain it briefly, but retaining some moisture is what helps these blondies stay soft.
Watch the bake time closely near the 25-minute mark. A toothpick with a few moist crumbs indicates a tender result, while baking until the toothpick is completely dry may produce firmer edges and a drier center.
For the frosting, allow the boiled butter and brown-sugar mixture to reach room temperature before adding the confectioners’ sugar. If the frosting seems thick after mixing, spread it promptly over the cooled bars while it is still workable.
For a breakfast-style gathering before dessert, recipes such as these pumpkin dinner rolls can complement the warm brown-sugar notes without competing with the zucchini blondies.
Serving, Storage, and Make-Ahead Advice
Serve the blondies at room temperature so the frosting is creamy and the crumb is soft. A sharp knife makes the cleanest cuts; wipe the blade between slices if you want especially tidy squares.
Store the frosted bars in a tightly covered container. They are easy to prepare ahead because the pan can be baked and cooled before the frosting is made, then finished once the bars are ready to serve.
- Keep the blondies in a single layer when possible so the frosting stays intact.
- For neat portions, chill the frosted pan briefly before cutting, then allow the bars to return toward room temperature before serving.
- Use leftover zucchini in a savory dish such as garlic herb sautéed mushrooms for a vegetable-focused meal before dessert.
These bars also travel well in a covered pan, making them suitable for potlucks, bake sales, family reunions, and casual afternoon coffee. Their simple appearance hides a particularly rich frosting, so they tend to disappear quickly from a dessert table.
Common Questions About Zucchini Blondies
Do I need to peel the zucchini? No. The peel is tender, adds a touch of color, and does not interfere with the soft texture when the zucchini is finely shredded.
Can I use very watery zucchini? Yes, with a small adjustment. Lightly blot or briefly drain exceptionally watery shreds, but do not squeeze away every drop because the retained moisture supports the tender crumb.
Why must the frosting cool first? The cooked brown-sugar mixture needs to cool to room temperature before the confectioners’ sugar is added. Adding sugar while the mixture is hot can create a frosting that is too thin, uneven, or difficult to spread.
How do I know the blondies are done? The center should look set, and a toothpick inserted in the middle should come out clean or with only a few moist crumbs. Begin checking at 25 minutes, since ovens and pan materials can vary.
Zucchini Blondies with Penuche Fudge Frosting
Ingredients
Method
- Heat the oven to 350°F (175°C) and grease a 13-by-9-inch baking pan.
- Beat the softened butter and packed brown sugar until blended. Add the egg and vanilla, then beat until combined.
- Whisk the flour, baking powder, and salt together in a separate bowl. Gradually add the dry ingredients to the butter mixture.
- Stir in the finely shredded zucchini just until it is evenly distributed. Spread the batter in the prepared pan.
- Bake for 25 to 30 minutes, until the center is set and a toothpick comes out clean or with only a few moist crumbs.
- Cool the blondies completely in the pan before frosting.
- For the frosting, melt the butter in a saucepan over medium heat. Stir in the brown sugar and milk, bring the mixture to a boil, and cook for 1 minute while stirring.
- Remove the frosting mixture from the heat and let it cool to room temperature. Gradually beat in the confectioners’ sugar and vanilla until smooth, then spread it over the cooled blondies.
Notes
Final Thoughts
Zucchini blondies with penuche fudge frosting bring together everything people love about homemade bar cookies: a buttery brown-sugar base, a soft and moist center, and a thick frosting that tastes like old-fashioned fudge. The zucchini quietly supports the texture while vanilla and caramel notes make each square feel rich and comforting.
Give the blondies time to cool completely, and be patient with the frosting mixture before adding confectioners’ sugar. Those two small details make the difference between a neat, creamy topping and one that becomes thin or difficult to spread.
Cut the finished pan into about 24 bars and serve them with coffee, tea, or a cold glass of milk. This recipe is simple enough for a weekday bake yet memorable enough to earn a place on a holiday or potluck dessert table.