Preheat your oven to 350°F and grease a 9x13 inch baking pan (or similar size) with butter or cooking spray. While the oven heats, whisk together the flour, cinnamon, nutmeg, baking soda, salt, and baking powder in a medium bowl. Set this dry mixture aside—this ensures your leavening agents are evenly distributed throughout the cake for consistent rise.

In a large bowl, beat the eggs until they're light and foamy—this incorporates air that helps the cake rise. Add the sugar gradually while continuing to beat, then pour in the oil, vanilla extract, and lemon zest. The lemon zest brightens the spice flavors beautifully and adds a subtle freshness that complements the zucchini. Beat until everything is well combined and the mixture looks pale and slightly thickened.

Pour the dry ingredient mixture from Step 1 into the wet batter from Step 2, folding gently with a spatula until just combined—don't overmix, as this can overdevelop the gluten and make the cake tough. A few small streaks of flour are fine; you want a tender crumb, not a dense one. Mix just until the flour disappears.

Gently fold the shredded zucchini (make sure it's well-squeezed to remove excess moisture, otherwise the cake will be soggy), chopped walnuts, and golden raisins into the batter. I prefer chopping the walnuts into smaller pieces so they distribute evenly throughout each slice rather than creating large pockets. Fold just until everything is evenly distributed—the batter should look speckled with green and studded with nuts and fruit.

Pour the batter into your prepared 9x13 inch pan, spreading it evenly with a spatula. Bake for 40 to 45 minutes, until a toothpick inserted into the center comes out clean or with just a few moist crumbs. The top should be golden brown and spring back when you lightly touch it. Remove from the oven and let the cake cool completely in the pan—this usually takes about an hour, and it's important to let it cool fully before frosting to prevent the frosting from melting.

While the cake cools, beat the softened cream cheese and room-temperature butter together in a bowl until smooth and creamy, about 2 minutes. Gradually add the powdered sugar and vanilla extract, beating until light and fluffy—this usually takes another 2 to 3 minutes of beating. I like to make the frosting while the cake is still cooling because it gives you time to get the texture just right, and the frosting will be at the perfect consistency by the time the cake is ready.

Once the cake is completely cooled, spread the cream cheese frosting evenly over the top using a spatula or offset knife. Cut into squares and serve at room temperature or slightly chilled. The combination of warm spices, tender crumb, tart-sweet frosting, and hidden zucchini makes this cake a crowd-pleaser.