Grate the zucchini on the large holes of a box grater into a colander set over a bowl. Toss with 1 tsp salt and let sit for 15 minutes to draw out water.

Squeeze the zucchini hard in a clean kitchen towel until no more liquid drips out. Set aside.

Preheat the oven to 200C / 390F. Brush a 30x40 cm rimmed baking sheet generously with 2 tbsp olive oil.

In a large bowl, whisk the eggs, milk, and remaining 3 tbsp olive oil until smooth.

Whisk in the flour a little at a time until the batter is smooth and lump-free, like a thin pancake batter.

Fold in the squeezed zucchini, Parmesan, onion, marjoram, and a generous grind of black pepper.

Pour the batter onto the prepared pan and spread evenly to about 1 cm thick, right to the edges.

Bake for 35 to 40 minutes until the top is deep golden brown and the edges are dark and crisp.

Cool for 10 minutes on the pan before cutting into squares. Serve warm or at room temperature.