Preheat oven to 200°C (400°F) or 180°C (350°F) fan and line a baking tray with parchment paper.
Place the fresh spinach in a large microwave-safe bowl, cover, and microwave on high for 3 minutes until wilted, or wilt on the stovetop with a splash of water in a skillet.
Allow the wilted spinach to cool slightly, then squeeze out as much liquid as possible using your hands, a muslin cloth, or strong kitchen paper to yield about 2/3 cup (130 g) cooked spinach.
Chop the squeezed spinach finely and transfer to a large mixing bowl.
Add the beaten eggs, grated cheddar, grated parmesan, almond flour, psyllium husk, garlic powder, onion powder, black pepper, chopped parsley, and 1/2 tablespoon olive oil to the bowl and mix until evenly combined.
Shape the mixture into balls using your hands, placing them on the prepared baking tray; you should get about 18 balls.
Brush or spray the tops with the remaining 1/2 tablespoon olive oil.
Bake for 20–23 minutes until golden on top, turning the tray or rotating balls after about 15–18 minutes for even browning.