3 Ingredient Chocolate Zucchini Cake Recipe (Cake Mix, Eggs, Zucchini) New

Five minutes of prep, no oil, and a tested ratio that keeps the center moist instead of gummy.

This 3 ingredient chocolate zucchini cake recipe uses 1 box of chocolate cake mix, 3 large eggs, and 2 cups (250 g) of shredded zucchini. You skip the oil and water listed on the box. Prep takes 5 minutes in one bowl, and each of the 12 squares comes to about 145 calories.

The full recipe comes first. Below it you’ll find a ratio chart, bake times for 6 pan sizes, and fixes for a gummy center.

3 Ingredient Chocolate Zucchini Cake Recipe Card

3 Ingredient Chocolate Zucchini Cake

A moist, no oil chocolate snack cake made with boxed cake mix, eggs, and shredded zucchini. One bowl and 5 minutes of prep.

Print Recipe Pin Recipe

Prep Time 5 minutes mins

Cook Time 35 minutes mins

Cooling 30 minutes mins

Total Time 1 hour hr 13 minutes mins

Course Dessert, Snack

Cuisine American

Servings 12 squares

Calories 145 kcal

Equipment

• 1 8×8 inch baking pan Light metal or glass. See the pan chart below for other sizes.
• 1 Large mixing bowl 3 quart or larger
• 1 Box Grater Use the large holes
• 1 Whisk For the eggs
• 1 Silicone spatula For folding and spreading thick batter
• 1 Kitchen scale or measuring cups A scale gives the most accurate zucchini amount
• 3 Paper towels For pressing the zucchini
• 1 Sheet of parchment paper Cut as a sling with 2 inch overhangs
• 1 Instant-read thermometer Optional, for checking 205°F at the center
• 1 Toothpick or paring knife For the doneness test
• 1 Wire cooling rack For cooling in the pan

Ingredients

  

• 15.25 oz. chocolate cake mix, devil’s food or chocolate fudge flavor Use the dry mix only
• 3 large eggs at room temperature. Swap in 3 flax eggs for a vegan cake
• 250 grams shredded zucchini lightly packed and unpeeled, pressed once with paper towels
• 2 tablespoons water or milk only if the batter is too stiff (optional).

Instructions

 

Prep the pan and zucchini

• Heat the oven to 350°F (175°C) with the rack in the center.
• Grease the pan and line it with a parchment sling.
• Trim the ends of the zucchini. If it’s longer than 12 inches, halve it lengthwise and scoop out the seeds.
  
• Grate the zucchini on the large holes of a box grater. Weigh 250 g, or measure 2 cups lightly packed.
• Spread the shreds on paper towels and press down once, firmly.

Mix the batter

• Whisk the eggs in the large bowl for 30 seconds, until smooth.
• Stir the zucchini into the eggs.
• Add the dry cake mix. Fold until no dry streaks remain, about 1 minute.
• If the batter won’t drop off the spatula, add water 1 tablespoon at a time, up to 3 tablespoons.
  

Bake

• Spread the batter evenly into the corners of the pan.
• Bake 32 to 38 minutes. Keep the door shut for the first 25 minutes.
• The cake is done when the top looks matte, a knife comes out with moist crumbs but no wet batter, and the center reads 205°F.
  

Cool and cut

• Cool the cake in the pan on the rack for 30 minutes. The center keeps setting as it cools.
• Lift the cake out by the parchment and cut it into 12 squares.

Notes

1. Weigh the zucchini. A lightly packed cup can vary a lot in weight, and 250 g keeps the center from turning gummy.
2. Press the zucchini instead of squeezing it. Squeezing removes moisture the cake needs.
3. Above 3,500 feet, add 1 tablespoon of flour and raise the oven by 15°F. Start checking at 28 minutes.
4. If you use frozen zucchini, thaw and drain it first, then weigh 250 g.
5. Wrap squares one at a time and freeze for up to 3 months.

Keyword 3 ingredient chocolate zucchini cake, cake mix zucchini cake, chocolate zucchini snack cake, no oil cake

Why This 3 Ingredient Cake Works

Cake mix already contains flour, sugar, cocoa, leavening, and emulsifiers. You only need to add moisture and structure. Zucchini brings the moisture, and eggs bring the structure.

Zucchini is about 95% water. Grated zucchini releases that water slowly as the cake bakes, so it replaces both the water and the oil on the box.

Eggs set the crumb because their proteins firm up with heat. They also trap air, which helps the leavening in the mix lift the cake.

How you balance these three ingredients matters more than which brand you buy.

Ingredients and What Each One Does

Chocolate cake mix

Check the weight on your box. Many boxed cake mixes shrank from 15.25 oz to 13.25 oz. This recipe works with either size. A 15.25 oz box makes a stiffer batter, so you may need to add 1 to 2 tablespoons of water.

Devil’s food and chocolate fudge flavors bake up darkest and hide the green flecks best. A gluten free cake mix also works, but it bakes into a more fragile crumb, so let it cool completely before you cut it.

Eggs

Use 3 large eggs at room temperature. They whisk smooth faster and blend into the thick batter in fewer strokes.

“Can I use 2 eggs instead?” Yes. You’ll get a denser, fudgier square that rises less. Add 3 to 5 minutes to the bake time.

To make it vegan, use 3 flax eggs. One flax egg = 1 tablespoon of ground flaxseed mixed with 3 tablespoons of water and rested for 10 minutes. The cake will rise less and the center will be softer. Check the cake mix label for milk ingredients too.

Zucchini

Two cups, lightly packed, weigh about 250 g. That’s roughly 1 large or 1.5 medium zucchini. Don’t peel it. The skin softens in the oven and blends into the dark crumb.

Got a garden zucchini longer than 12 inches? Cut it in half lengthwise and scoop out the seeds, because large seeds stay chewy after baking. Yellow summer squash works as a 1:1 swap.

Grate the zucchini on the large holes of a box grater. The fine holes turn it to pulp, which dumps water into the batter too fast.

Weighing tells you more than measuring cups do, and the ratio chart below shows why.

How Much Zucchini and How Many Eggs?

Changing the eggs or the zucchini changes the crumb more than any other choice you make. Use this chart to pick the texture you want. Every version bakes in an 8×8 metal pan at 350°F with a 13.25 oz chocolate fudge mix and comes out when the center reads 205°F.

These times are starting points. Your oven and your box will shift them by a few minutes.

Three eggs with 250 g of zucchini gives you the best balance of rise and moisture. Two eggs make a fudgier square that rises less. Extra zucchini adds water that keeps the middle cool, so the center sets later than the edges and can turn gummy.

Shredded zucchini starts releasing water as soon as you grate it. One firm press between paper towels removes the surface water and leaves the rest in the shreds. Wringing it in a towel removes far more, and the cake bakes up drier and more crumbly. Do NOT wring it dry. You need most of that water.

The dark chocolate mix hides both the green flecks and the mild zucchini flavor.

With your ratio set, the only steps left are mixing and checking for doneness.

Mixing and Doneness Tips

Whisk the eggs first, then stir in the zucchini, then fold in the dry mix. The batter should be thick and scoopable, like brownie batter. If it won’t drop off your spatula, add water 1 tablespoon at a time.

Spread the batter into the corners of the pan and keep the oven door shut for the first 25 minutes.

Chocolate cake doesn’t brown, so you need other signs. The top turns from shiny to matte when it’s done. A paring knife shows wet crumbs more clearly than a toothpick does. Most cakes finish between 200 and 210°F inside.

“Do I really need a thermometer?” No, but an instant-read thermometer takes the guesswork out of a moist zucchini batter. Use it alongside the matte top and knife test, and pull the cake at 205°F. Egg mixtures are safe at 160°F, so a finished cake is well past that point.

Your pan size changes the bake time more than anything else.

Pan Size and Bake Time Chart

Bake at 350°F and start checking at the low end of each range.

(Ed. note. Dark metal pans bake faster. Check 5 minutes early or lower the oven to 325°F.)

That settles the pan. Skipping the oil also cuts calories.

Calories and Cost vs Box Directions

A 13.25 oz box of chocolate fudge mix has about 160 calories per 1/9 of the package, or about 1,440 for the whole box. Check your label, since brands vary. Three large eggs add about 234 calories, and 250 g of zucchini adds about 42. That totals about 1,716 calories, or 143 per square when you cut 12.

Can I just add the oil anyway? You can, but it costs you. Oil has about 120 calories per tablespoon. If your box calls for 1/2 cup, that adds about 960 calories, or 80 per square.

Is it health food? No. A typical chocolate mix has 17 g of added sugar per 1/9 package, or about 13 g per square. The zucchini adds about 4 mg of vitamin C per square. Treat it as a lighter dessert.

Even a good ratio can go wrong in your oven. Each common problem has a quick fix.

Troubleshooting

A gummy center comes from too much zucchini, unblotted zucchini, or underbaking. Weigh 250 g, press it once, and bake to 205°F.

“Why did it sink after cooling?” The center was underbaked, the pan was too small, or the oven door opened too early. Bake 3 to 5 minutes longer, or switch to a 9×9 pan.

Dry edges come from dark pans or overbaking. Lower the oven to 325°F or check 5 minutes sooner.

To stop sticking, grease the pan and line it with a parchment sling.

At high altitude, raise the oven 15°F and add 1 tablespoon of flour.

Once the basic cake works, you can change it up.

Variations and Toppings

Stir in 3/4 cup of mini chocolate chips after you add the mix. For double chocolate, add 1 tablespoon of cocoa powder and 1 teaspoon of espresso powder.

Spice or carrot cake mix makes a cake mix zucchini cake with a different flavor. Light mixes like yellow cake will show green flecks.

Keep the topping simple. A 2 ingredient glaze of 1 cup powdered sugar whisked with 2 tablespoons of milk sets in 15 minutes. You can also dust the top with powdered sugar or serve each square with a spoonful of Greek yogurt.

Whichever version you make, you store it the same way.

Storage and Freezing

“Can I leave it out overnight?” Yes. Keep it covered on the counter for up to 2 days. For longer storage, refrigerate it for 3 to 4 days or freeze it for up to 3 months.

Wrap squares one at a time before freezing. Move one to the fridge the night before you pack a lunchbox.

If you freeze shredded zucchini, thaw it in a strainer and press out the pooled liquid. Then weigh 250 g after draining.

FAQ

Bake It Today

This 3 ingredient chocolate zucchini cake recipe turns one big zucchini into 12 squares at about 145 calories each. Weigh the zucchini, press it once, and pull the cake at 205°F. Save the pin so you have the pan chart ready next time your garden overproduces.

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