Preheat the Oven: Preheat your oven to 375°F (190°C).

Prepare the Vegetables: Grate the zucchini, potato, and carrot. Finely chop the onion. Place the grated vegetables in a clean kitchen towel and squeeze out any excess moisture.

Combine Ingredients: In a large bowl, combine the grated vegetables, chopped onion, eggs, flour, salt, pepper, and shredded cheese (if using). Mix well until all ingredients are fully incorporated.

Pour and Bake: Pour the mixture into a 6-inch non-stick cake pan or any oven-safe dish. Smooth the top with a spatula for even baking.

Bake: Place the pan in the preheated oven and bake for 1 hour, or until the frittata is golden brown on top and cooked through.

Cool and Serve: Allow the frittata to cool slightly in the pan before slicing. Serve warm, and enjoy!