Preheat the oven to 350°F (175°C) and place a rack in the center.

Grease a 9x13-inch baking pan and line the bottom with parchment paper (leave an overhang for easy removal).

If you’d rather skip the parchment, thoroughly grease and flour the pan or use a nonstick spray.

Pro tip: Lining the pan with parchment makes it much easier to lift the cake out cleanly for cooling and slicing.

Wash the zucchini, trim the ends, and do not peel.

Grate on the small side with a box grater or use the shredding disk in a food processor.

Pack the grated zucchini into a measuring cup until you have 2 cups.

Pro tip: If the zucchini looks extra watery (older or very large), let it sit in a mesh strainer 5–10 minutes and gently blot with paper towels — just enough to remove excess surface water. Don’t squeeze it dry or you’ll lose moisture that keeps the cake tender.

In a large bowl, whisk together: 2 cups all-purpose flour, 2 tsp baking powder, 1 tsp baking soda, 1 tsp ground cinnamon, ½ tsp ground nutmeg, and ½ tsp salt.

Whisk until the mixture is uniform and there are no large clumps.

Pro tip: Whisk continuously to prevent lumps and to aerate the flour slightly — this helps a lighter crumb.

In a separate bowl, beat 3 large eggs briefly, then add 1 cup granulated sugar and 1 cup packed light brown sugar. Mix until sugars are mostly dissolved and the mixture looks glossy.

Stir in 1 cup vegetable oil and 2 tsp vanilla extract until combined.

Pro tip: You don’t need to whip this into a mousse — just blend until cohesive. Overbeating here will not help and can change the texture.

Pour the wet mixture into the bowl with the dry ingredients. Using a spatula, stir until the flour is just incorporated — stop when you no longer see white streaks of flour.

Fold the 2 cups grated zucchini into the batter until evenly distributed. If you want to add nuts or raisins, fold them in now (about 1 cup chopped nuts or ¾ cup raisins).

Pro tip: Folding gently keeps the cake tender. Overmixing develops gluten and makes the cake dense.

Scrape the batter into the prepared 9x13 pan and use an offset spatula or the back of a spoon to smooth the top evenly.

Tap the pan gently on the counter once or twice to release any large air bubbles.

Bake at 350°F (175°C) for 30–40 minutes. Start checking at about 28–30 minutes.

The cake is done when a toothpick inserted into the center comes out with a few moist crumbs (not wet batter), the top is lightly golden, and the edges have pulled slightly from the pan.

Pro tip: If you use a glass pan, check a little earlier—glass retains heat and can speed up baking. If the top is browning too quickly, loosely tent with foil for the last 10 minutes.

Let the cake cool in the pan on a wire rack for 10–15 minutes.

Use the parchment overhang to lift the cake out onto the wire rack and cool completely before frosting.

If you prefer to leave it in the pan, cool fully on the rack — just know it will retain more moisture that way.

Pro tip: For cream cheese frosting, the cake must be completely cool; otherwise the frosting will melt and slide.

Beat 8 oz softened cream cheese with ½ cup softened butter until smooth.

Gradually add 3 cups powdered sugar and 1 tsp vanilla extract, beating until light and spreadable. If the frosting is too thick, add 1–2 tablespoons milk. If too soft, chill 10–15 minutes.

Pro tip: Always use room-temperature cream cheese and butter to achieve a lump-free, silky frosting.

Spread the frosting evenly over the cooled cake. For cleaner slices, chill the frosted cake for 15–30 minutes before cutting.

Store slices in an airtight container: at room temperature for 1–2 days, or refrigerated for up to 5 days (frosted cake should be refrigerated). To freeze, wrap slices tightly and freeze up to 3 months.

Pro tip: Wipe your knife between cuts with a damp cloth for neat, clean slices.