Step-by-Step Preparation
1. Set the Stage Preheat your oven to 180°C (350°F). Grease a loaf pan or a round cake tin with a bit of olive oil, or line it with parchment paper to ensure an easy release later on.
2. The Secret is in the Slice Wash your zucchini and trim the ends. The "invisible" effect depends entirely on the thickness of the slices. Using a mandoline or a very sharp knife, cut the zucchini into paper-thin rounds or long ribbons. You want them so thin they are almost translucent.
3. Whisk the Custard In a large mixing bowl, beat the eggs until they are light and frothy. Whisk in the milk and olive oil until well combined. Gradually sift in the flour and baking powder, stirring until the batter is completely smooth and free of lumps.
4. Flavor and Fold Stir in the grated Parmesan, salt, pepper, and your choice of herbs. Now, add the zucchini slices to the bowl. Use a spatula to gently fold them into the batter, making sure every single slice is coated in the liquid. It might look like there is too much zucchini and not enough batter, but don't worry—that is exactly how it should look!
5. Bake to Perfection Pour the mixture into your prepared tin, smoothing out the top so the slices lie flat. Bake for 35 to 40 minutes. You are looking for a beautiful golden-brown crust on top and a center that feels firm to the touch.
6. The Final Rest This is the hardest part: let it cool. Allow the cake to sit in the tin until it is lukewarm before attempting to unmold it. This resting period allows the layers to "set" so you get those perfect, clean slices.