Start by preheating your oven to 200°C (390°F) and lining a baking sheet with parchment paper. Rinse the spinach well, then squeeze out all excess moisture and chop it finely. Dice the onion into tiny pieces.
Heat a tablespoon of olive oil in a large skillet over medium heat. Add the diced onion and cook until it becomes translucent and fragrant, about 3 minutes. Then, add the chopped spinach and cook just until wilted, about 2 minutes. Remove from heat and let cool slightly.
Transfer the cooked greens and onions to a mixing bowl. Add the crumbled feta or Parmesan, panko breadcrumbs, and beaten egg. Mix everything thoroughly until the mixture is cohesive and can be pressed into patties. If it feels too loose, sprinkle in a little more breadcrumbs.
Shape the mixture into small, flat patties about 2 inches in diameter and 1/2 inch thick. Place them on your prepared baking sheet, spacing them evenly. Lightly brush the tops with olive oil for extra crunch and golden color.
Bake the patties in the preheated oven for 15-20 minutes, flipping them halfway through, until they turn a beautiful golden brown and develop a crispy exterior. The smell of toasted cheese and greens will fill your kitchen.
Once baked, transfer the patties to a wire rack and let them rest for 2 minutes. This helps keep them crispy and firm. Serve warm, perhaps with a squeeze of lemon or a dollop of yogurt for extra flavor.
