1. Rinse the spinach, roughly chop it, and reduce it in a pan with a little olive oil.
2. Finely slice the onion.
3. Separate the egg whites from the yolks.
4. In a bowl, mix the flour, baking powder, and spices. Then add the sliced onion, egg yolks, milk, and cooled melted butter, followed by the cooked spinach.
5. Beat the egg whites until stiff peaks form. Gently fold them into the batter using a spatula, without overmixing.
6. Heat a pan with a little olive oil, then drop a large spoonful of batter onto it. When the edges are firm and small bubbles appear in the center, add a few mint leaves and flip the pancake. Cook until golden.
7. Serve with a little feta cheese and lemon juice.