Preheat your oven to 180°C (350°F) and prepare a square baking dish by greasing it or lining the bottom with parchment paper.

Sauté the chopped onion and minced garlic in olive oil over medium heat until soft and fragrant—about 3–4 minutes. Add the spinach and cook until just wilted.

Mix the eggs, milk, and olive oil together in a large bowl until combined.

Stir in the all-purpose flour, baking powder, salt, ground black pepper, and dried oregano or dill to create a thick batter.

Fold the cooled spinach mixture and crumbled feta cheese gently into the batter.

Pour the batter into the prepared baking dish and smooth the top with a spatula.

Bake for 35–40 minutes or until the top is golden brown and a toothpick inserted comes out clean.

Cool the bake for at least 10 minutes before transferring to a cutting board.