Why lemon and zucchini work together
Zucchini has a mild flavor and adds moisture to cake, much like carrot does in carrot cake (compare our lighter Italian orange carrot cake). Lemon zest and juice brighten the crumb, and the zucchini mostly disappears into the texture, leaving green flecks. A tangy cream cheese frosting with lemon balances the sweetness. This is a good way to use extra summer zucchini.
Ingredients
This makes one 9x13-inch (23x33 cm) cake, or a two-layer 8-inch cake.
For the cake:
- 2 cups (250 g) all-purpose flour
- 1 1/2 teaspoons baking powder
- 1/2 teaspoon baking soda
- 1/2 teaspoon salt
- 1/2 teaspoon ground cinnamon (optional)
- 1 cup (200 g) granulated sugar
- 1/2 cup (120 ml) neutral oil
- 2 large eggs
- 1/2 cup (120 ml) whole milk
- Zest of 2 lemons
- 2 tablespoons fresh lemon juice
- 1 teaspoon vanilla extract
- 1 1/2 cups (about 180 g) grated zucchini, unpeeled
For the lemon cream cheese frosting:
- 8 ounces (225 g) full-fat brick cream cheese, softened
- 1/4 cup (55 g) unsalted butter, softened
- 2 cups (240 g) powdered sugar
- 1 teaspoon vanilla extract
- 1 to 2 tablespoons fresh lemon juice, to taste
- Zest of 1 lemon
Preparing the zucchini
Grate the zucchini on the large holes of a box grater. Wrap it in a clean towel or paper towels and squeeze out some of the liquid, but don’t wring it completely dry. A little moisture helps keep the cake tender. If the zucchini is very watery, squeezing more helps avoid a gummy crumb. Peeling is optional; the skin is thin and gives the green flecks.
Make the cake
- Heat the oven to 350°F (175°C). Grease and flour a 9x13-inch pan, or line it with parchment.
- Whisk the flour, baking powder, baking soda, salt, and cinnamon.
- In another bowl, whisk the sugar, oil, eggs, milk, zest, lemon juice, and vanilla until smooth.
- Pour the wet mixture into the dry and stir just until combined (the muffin method), then fold in the zucchini.
- Pour into the pan and bake about 30 to 40 minutes, until a toothpick comes out clean. For 8-inch round layers, start checking around 25 to 30 minutes.
- Cool completely in the pan or on a rack before frosting.
Lemon cream cheese frosting
Beat the cream cheese and butter until smooth and creamy. Add the powdered sugar a little at a time, then the vanilla, zest, and lemon juice. Add the juice slowly, since too much will loosen the frosting. If it is soft, chill it for 15 to 30 minutes before spreading.
Assembly and serving
Spread the frosting over the cooled cake, using the back of a spoon for swoops. For a layer cake, spread a generous layer between the cakes and frost the top. Garnish with extra zest or thin lemon slices. Chill for a short while before slicing for cleaner pieces.
Tips and troubleshooting
- Cake feels wet or gummy: the zucchini may have been very juicy. Squeeze more next time and bake until the center is fully set.
- Frosting is runny: the cream cheese or butter was too warm, or too much juice was added. Chill it or add a bit more powdered sugar.
- Lemon flavor is weak: add more zest. Zest carries more aroma than juice.
- Frosting tastes too sweet: use a little less powdered sugar and a bit more lemon.
- Use brick cream cheese, not the spreadable tub type, which is softer.
- Don’t overmix once the flour is added.
Storage and make-ahead
Because of the cream cheese frosting, keep the frosted cake covered in the refrigerator, and eat within about 3 to 4 days. Let slices sit out briefly before serving. You can bake the cake a day ahead, wrap it, and frost it on the day of serving. Unfrosted cake can be frozen wrapped well.
More lemon cakes
For something lighter and rolled, try lemon cake rolls. If you like a custardy lemon cake, the Irish lemon cake is a simple alternative.