Preheat your oven to 375°F (190°C) so it has enough time to fully heat while you prepare the casserole ingredients. Lightly grease a medium-sized baking dish with extra virgin olive oil, coating the bottom and sides evenly to prevent sticking and help the edges develop a beautiful golden finish during baking.

Place a large skillet over medium heat and add the olive oil. Allow the oil to heat until it becomes lightly shimmering but not smoking. Heating the oil properly before adding the vegetables helps them cook evenly and develop deeper flavor instead of steaming.

Add the diced onion to the hot skillet and cook for about 3–4 minutes, stirring occasionally with a wooden spoon or spatula. The onions should become soft, slightly translucent, and lightly golden around the edges, which helps build a naturally sweet and savory flavor base for the casserole.

Stir in the minced garlic and cook for another 30 seconds, stirring continuously so the garlic becomes fragrant without burning. Garlic cooks quickly, so keeping the heat moderate helps preserve its flavor while avoiding bitterness.

Add the sliced zucchini, halved cherry tomatoes, and sweet corn kernels to the skillet. Stir everything together gently so the vegetables are evenly coated in the olive oil and aromatics. Cook for about 5–7 minutes until the zucchini begins to soften slightly and the tomatoes release some of their juices while still holding their shape. Avoid overcooking the vegetables at this stage because they will continue cooking in the oven.

While the vegetables cook, crack the eggs into a large mixing bowl and add the Greek yogurt, shredded mozzarella cheese, grated Parmesan cheese, oregano, turmeric, black pepper, and sea salt. Whisk everything together thoroughly until the mixture becomes smooth, creamy, and evenly combined with no streaks of yogurt remaining.

Carefully transfer the sautéed vegetable mixture into the prepared baking dish and spread it into an even layer. Try to distribute the zucchini, tomatoes, onions, and corn evenly throughout the dish so every slice contains a balanced combination of ingredients.

Slowly pour the egg and cheese mixture evenly over the vegetables. Use a spoon or spatula to gently stir everything together just slightly, allowing the creamy mixture to settle into the vegetables without completely disturbing their arrangement.

Place the baking dish into the preheated oven and bake for 30–35 minutes until the center is fully set and the top becomes beautifully golden brown. The casserole should look lightly puffed with slightly crisp edges and melted cheese bubbling gently on top.

Remove the casserole carefully from the oven and place it on a heat-safe surface. Allow it to rest for about 5–10 minutes before slicing. Resting helps the casserole firm up slightly so the slices hold together better when served.

Just before serving, sprinkle freshly chopped parsley evenly over the top for a burst of freshness and color. Serve the vegetable bake warm as a comforting healthy main dish, meal prep lunch, or flavorful side alongside grilled chicken, salmon, or a fresh Mediterranean-style salad.