Grate the zucchini and sprinkle with half the salt. Let it sit for 10 minutes, then squeeze out excess moisture using a clean kitchen towel or cheesecloth.
Grate the potato and do the same—removing as much water as possible.
In a large mixing bowl, whisk together the eggs, milk, vegetable oil, sugar, remaining salt and pepper.
Add in the flour and baking powder, stirring until a smooth batter forms.
Fold in the grated zucchini and potato, mixing until evenly combined.
Preheat your oven to 375°F (190°C). Lightly grease a baking dish or ovenproof skillet with olive oil.
Pour the batter into the dish and drizzle the top with remaining olive oil.
Bake for 35–40 minutes, or until the top is golden brown and a toothpick comes out clean.
Let cool for 5 minutes before slicing. Serve warm or at room temperature.