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Two stacked squares of 3 ingredient chocolate zucchini cake on a white plate showing a moist crumb

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.
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Prep Time 5 minutes
Cook Time 35 minutes
Cooling 30 minutes
Total Time 1 hour 13 minutes
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.
    Zucchini shredded on the large holes of a box grater and weighed to 250 g on a kitchen scale
  • 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.
    Thick chocolate zucchini cake batter dropping from a silicone spatula into a glass bowl

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.
    Shiny underbaked chocolate cake center next to a matte baked top with a knife and thermometer reading 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