Chocolate Zucchini Cake

Before you start

Grated zucchini disappears into this chocolate cake. It adds moisture and tenderness without any vegetable taste, making a soft, rich crumb that stays moist for days. It is a good use for a summer glut of zucchini, and the cake needs no frosting; chocolate chips scattered on top melt into a light glaze.

How you treat the zucchini matters. Grate it on the large holes of a box grater and squeeze it lightly, removing some water but not all. Squeezing it dry makes a drier cake; leaving it wet makes the center gummy. Weigh the grated zucchini after squeezing. Older, larger zucchini have big, watery seeds; scoop those out before grating.

Ingredients

• 250 g (2 cups, spooned and leveled) all-purpose flour
• 40 g (½ cup) unsweetened natural cocoa powder
• 1 tsp baking soda
• ½ tsp baking powder
• ¾ tsp fine salt
• 1 tsp ground cinnamon
• 200 g (1 cup) granulated sugar
• 100 g (½ cup, packed) light brown sugar
• 120 ml (½ cup) neutral oil
• 60 g (4 tbsp) unsalted butter — melted
• 2 large eggs — room temperature
• 120 g (½ cup) plain yogurt or buttermilk
• 2 tsp vanilla extract
• 300 g (about 2½ cups) grated zucchini — about 2 medium, lightly squeezed and weighed after
• 170 g (1 cup) semisweet chocolate chips

Method

1. Heat the oven to 175°C (350°F). Grease the pan and line it with parchment.
2. Grate the zucchini on the large holes of a box grater. Wrap it in a clean towel and squeeze gently over the sink until it stops dripping freely but still feels damp. Weigh out 300 g.
3. Whisk the flour, cocoa, baking soda, baking powder, salt and cinnamon in a bowl.
4. In a larger bowl, whisk both sugars with the oil and melted butter, then whisk in the eggs, yogurt and vanilla until smooth.
5. Add the dry ingredients and fold until just combined. Fold in the zucchini and half the chocolate chips. The batter will be thick.
6. Spread it in the pan and scatter the remaining chips over the top.
7. Bake for 35 to 40 minutes, until the center springs back and a toothpick comes out clean apart from melted chocolate.
8. Cool in the pan on a rack for at least 45 minutes before cutting into 16 squares.

Tips for success

• Do not peel the zucchini. The thin green skin melts into the dark crumb and adds a little structure.
• If you have more zucchini, grate and squeeze it, then freeze it in 300 g portions. Thaw and drain before using.
• The cake gets moister on the second day, so it is a good make-ahead choice.

Substitutions

Yogurt

Use sour cream for a richer cake, or buttermilk for a slightly lighter crumb.

All-purpose flour

Replace up to half with whole wheat pastry flour. The cake becomes a little nuttier and denser.

Zucchini

Yellow summer squash works the same way. The cake looks the same since the dark crumb hides any color.

Variations

Chocolate zucchini muffins

Fill 18 lined muffin cups three-quarters full and bake for 20 to 24 minutes.

Mocha zucchini cake

Dissolve 2 tsp instant espresso in the yogurt before mixing.

Troubleshooting

Center is gummy

The zucchini was too wet or the cake was underbaked. Squeeze until it stops dripping and bake until the center springs back.

Cake is dry

The zucchini was squeezed completely dry or the cake overbaked. Leave some moisture in the zucchini and start checking at 33 minutes.

Green specks are visible

Thick zucchini shreds can show in the crumb. Use the large holes of a box grater and chop any long strands.

Storage

Cover and store at room temperature for up to 2 days, then refrigerate for up to 3 more because of the moist zucchini. The cake freezes well, wrapped, for up to 2 months.

Safety notes

Do not taste raw batter, which contains raw flour and egg. Wash zucchini under running water before grating. Contains wheat, egg and milk.